After the explosive events of her high school graduation, Buffy experienced difficulties adjusting to life as a college freshman at U.C. Sunnydale. She was injured during an encounter with a group of on-campus vampires, and came off as unstable to her friends when she suspected her overly compulsive roommate to be demon and she began rooming with Willow after Kathy's departure. Her troubles were only worsened by Angel's recent departure. She sought comfort with fellow student Parker Abrams, and slept with him only a few weeks after meeting him. He then brushed her off as a one-night stand despite making her believe that this was the start of a new relationship.

Her experience with Parker was made more difficult by Spike, who had returned to Sunnydale after Drusilla left him once again. He uncovered the Gem of Amara'a ring that made any vampire who wore it invulnerable to vampiric weaknesses' and attacked her on campus. Though she managed to defeat him and take the ring back, Spike escaped into the sewers. At Buffy's request, Oz delivered the Gem to Angel in Los Angeles.

During Thanksgiving, Buffy was forced to deal with Hus, the vengeful spirit of a Native American warrior, after he was released by Xander's construction crew. Buffy who had been determined to have a safe and normal holiday meal with her friends was also shocked when Spike arrived unexpectedly at Giles' flat, begging for help. Spike had been captured by the mysterious Initiative; a group of army-clad individuals Buffy had previously encountered on campus who implanted Spikewith a cerebral micro-chip that made it impossible for him to harm humans. Buffy was aided in the battle against Hus by Angel, who had returned to Sunnydale without her knowledge. When Xander accidentally revealed that Angel had reappeared, Buffy immediately traveled to Los Angeles to confront him as she was hurt that he had spoken to everyone but her. Buffy and Angel agreed to remain apart; just as she was about to leave, they were attacked by a Mohra Demon. They tracked the demon down into the sewers and succeeded in wounding it before it escaped. The demon's blood had mixed with Angel's during the confrontation, causing him to become human again. Buffy i will remember you Buffy and Angel realize they can never have a normal life together, even if he's human Buffy and Angel reveled in finally being able to be together, but Angel soon discovered that The Powers That Be had not yet offered him redemption. When Angel was almost killed by the regenerated Mohra demon, Buffy managed to slay it. After Angel discovered that Buffy would die much sooner if he remained human, Angel had the the Oracles rewind time to reverse his transformation into a human. Buffy was left with no memory of the incident.

Back in Sunnydale, Buffy and the Scoobies kept Spike tied up in Giles' flat as he bartered information about the Initiative for shelter and blood. At school, Buffy eventually attracted the sincere attention of her psychology teacher's assistant, Riley Finn, and began to wonder how she could balance her Slayer duties while dating a seemingly-normal boy. While fighting the Gentlemen, however, Buffy came to discover that Riley had a secret of his own; he was a member of the Initiative, which Buffy learned was a government task force created to research mystical and demonic creatures led by Buffy's psychology professor, Maggie Walsh.[53] Buffy briefly joined forces with the Initiative, but her relentless questioning of the organization's motives, as well as her relationship with Riley, began to unsettle Professor Maggie Walsh, who tried to have her killed in action. Walsh was subsequently murdered by a creature of her own creation, the monstrous half-human/half-demon cyborg, Adam, who then escaped and began his plan to create an army of super soldiers like him.

Faith then awakened from her coma and used a mystical device left to her by the Mayor to switch bodies with Buffy. In Faith's body, Buffy was taken into custody by the Watchers Council Special Operations Team. She managed to escape and convince Giles of her true identity. With the help of Willow and Tara Maclay, Buffy reversed the body swap. Upon discovering that Faith had traveled to Los Angeles and was attempting to kill Angel, a furious Buffy traveled to L.A. for vengeance, only to discover that Faith had become remorseful for her crimes. This put Buffy into direct conflict with Angel, who insisted that Faith could be rehabilitated. Though understandably unwilling or unable to believe that Faith was capable of redemption, Buffy ultimately had no choice but to work together with her to fight back against the Watchers Council Special Operations Team. Faith subsequently surrendered herself to the police, and Buffy got into a heated exchange with Angel, climaxing when she used her relationship with Riley to put Angel on the defensive, who then harshly ordered her to go back to Sunnydale after reminding her that he himself could not move on from their relationship. Angel subsequently returned to Sunnydale to apologize, and after running afoul of the Initiative in the process, succeeded in mending things with Buffy, with both sides admitting that they had been wrong.

Riley, who had been torn between the Scooby Gang and the Initiative for some time, eventually turned his back on the corrupt organization to join Buffy after helping them save Oz from the Initiative complex. Having been drifting apart for the previous year, the existing tensions between Buffy, Giles, Willow, and Xander reached their boiling point when Spike, wanting to have the chip removed from his head, exploited them to turn the gang against each other as part of Adam's plan. When Spike let too much information about the plot slip during an encounter with Buffy, causing the Scoobies to reconcile and combined their essences within Buffy's body, allowing her to destroy Adam.

The Scoobies, helped by Riley and Spike, subsequently helped save the Initiative's soldiers from the rampaging demon hordes within the complex; the Initiative was subsequently closed down by the U.S. government, and Riley was honorably discharged from the military. The four were later attacked in their dreams by the First Slayer, who was offended by their use of the adjoining spell to defeat Adam; Buffy promptly rejected the First Slayer's insistence that the Slayer work alone without friends.

Soon after her confrontation with the First Slayer, Buffy started to wonder about what it meant to be the Slayer and this encouraged her to start patrolling every night. On one of these patrols she encountered the world-renowned vampire Dracula, who had traveled to Sunnydale with the intention of making the legendary warrior his bride. Buffy among others was at first left powerless to Dracula's unique "thrall", but managed to overcome his control over her and forced him to leave town. Her battle against the infamous Count combined with her encounter with the First Slayer made Buffy realize the inherent "darkness" behind the Slayer legend and made her want to learn more about the other slayers. She began to fully accept her duty as the Slayer for the first time in her life, and enlisted Giles to put her through more extensive training in order to make her a better Slayer.

Meanwhile, a younger sister, Dawn, had mysteriously appeared in the Summers' household; her existence had been seamlessly integrated into the memories of all those she had ever known. After casting a spell on herself in the hopes of discovering the mystical source of an illness she believed her mother was blighted by, Buffy discovered that Dawn was not her sister at all, but rather a ball of magical energy known as the Key capable of opening interdimensional portals. A group of monks had influenced the Key to take human shape in order to protect it from a mentally unstable Higher Power known as Glorificus; they had chosen to put the Key in the Slayer's care, as a sister, in the hopes that she would protect it with her life. Though Buffy was understandably skeptical of Dawn when she learned that she had been fabricated and integrated into her life without her prior knowledge, she quickly came to accept her responsibility as Dawn's protector, not because she felt obliged to carry out the monks' wishes, but because she slowly realized that she truly did love her sister, regardless of the circumstances of her existences.

Buffy continued to patrol Sunnydale and fight evil with the Scoobies, despite the looming threat of Glory. After an encounter with an average vampire left her badly wounded, she became interested learning the deaths of past Slayers, and poured through old Watchers' records with Giles in an attempt to better understand her situation. She eventually went to Spike for information instead, who, having killed two Slayers in his lifetime, proved particularly knowledgeable on the subject. He brought her to the Bronze, where he recounted to her the events of his life in great detail, from his human life as William Pratt, to his siring by Drusilla, his rivalry with Angelus and his obsession with Slayers. He imparted to her his own personal philosophy in regards to Slayers that everyone has a death wish before she shoved him to the ground and returned home, where she had to confront her mother's worsening state. As she cried on the back porch, Spike suddenly appeared; though he at first seemed frustrated and intent on harming her for her prior words, upon seeing her in distress, he abandoned his pointless vendetta and comforted her for the first time.

Buffy's relationship with Riley slowly began deteriorate as she repeatedly failed to give him the emotional intimacy he craved. Riley began visiting a vampire brothel where he would allow vampires to bite him; when Buffy discovered this as a result of Spike's interference, she destroyed the brothel and confronted Riley, after which he left her and returned to the military. Buffy dealt with Riley's departure as best as she could, but remained emotionally sensitive. Buffy's pain over having had two failed relationships caused her to take an interest in Ben Wilkinson, a handsome medic. However, an encounter with the love-struck robot girlfriend of one of her former Sunnydale High classmate Warren Mears made hers realize that she was overly dependent on men and decided she needed to be by herself for a while. This proved to be greatly fortunate as Ben was secretly Glory's human vessel.

Watchers Council eventually came to Sunnydale with information about Glory, but refused to give it up until Buffy passed a test they had prepared for her. The Council interviewed Buffy's friends and allies in order to ascertain if she was "worthy" of the knowledge they had to deliver. Though Buffy at first failed to meet their high standards, it was through a conversation with Glory that gave her the confidence to stand up to the Council. Through a rousing speech, she managed to convince them to give her all the information they and reinstate Giles into the Council as her paid Watcher. With the Council's knowledge, Buffy discovered Glory was not a demon at all, but a god.

Later, Dawn casually revealed to Buffy that Spike had fallen in love with her, much to Buffy's surprise and disgust. She confronted him about it on a stakeout; while she attempted to tell him that his feelings were impossible, he kidnapped her in order to proclaim his devotion to her via murdering his sire and ex-lover, Drusilla. Buffy managed to escape, and subsequently alienated Spike from the Scoobies and had Willow recant his invitation into her house something she had not bothered to do since he first helped her during their fight against Angelus.

Buffy and Dawn were then devastated by the death of their mother shortly after. Joyce had been experiencing health problems for months, and only recently received surgery for a brain tumor when she died unexpectedly from an aneurysm. In order to fully take up her role as Dawn's legal guardian, Buffy was forced to drop out of college, though she faced difficulties as a result of Dawn's increasingly rebellious behavior. Meanwhile, Giles decided to take Buffy on a vision quest to help her discover that being the Slayer truly meant. In involved the First Slayer, her vision guide, cryptically telling her that death was her "gift." Buffy found such a message both confusing and hurtful so soon after her mother's passing, and immediately returned to Sunnydale. Upon her return, she discovered that Spike forced Warren to build a robotic sex toy in her likeness, which had resulted in him being captured by Glorificus' minions in belief that he was the Key. Despite her understandable rage and disgust over the robot's existence, Buffy saved Spike and subsequently discovered that he had endured intense torture and come close to dying at the hands of Glory in order to protect Dawn's identity as the Key. Moved by his sacrifice, Buffy rewarded Spike with a kiss and reconciled with him, welcoming him back into her circle of friends.

When Glory finally discovered that Dawn was the Key, Buffy immediately had her and the gang rushed out of Sunnydale in a Winnebago piloted by Spike. This attempt was hampered when the Knights of Byzantium, a militia intent on killing the Key to stop Glory, attacked the Scoobies on the road. The Scoobies then held up inside an abandoned gas station and called in Ben to treat Giles who had been injured in the assault. He then unwillingly turned into Glory who kidnapped Dawn, despite Buffy and the others' attempts to protect her. Believing she had failed, Buffy broke down retreated into her subconscious, where she battled with the guilt of having failed to protect her sister. Via magic, Willow successfully dove into Buffy's mind and helped her overcome her helplessness.

Although she knew that Dawn's death would destroy Glory's plan for good, Buffy refused to allow her sister to be harmed. She prepared for the battle with the Scoobies; whilst retrieving weapons from her house, she granted Spike permission to enter again, after which he expressed his gratitude to her for treating him "like a man." Buffy and the others subsequently attacked Glory's stronghold in full force. Willow weakened Glory's mentality, while Xander hit her with a wrecking ball and Buffy beat her repeatedly with a mystical troll god's hammer, before she finally reverted to Ben's weaker form. Not wanting to kill an innocent human, Buffy allowed Ben to live, warning him not to go after Dawn again. Giles, however, knew that Glory would rise again and killed Ben with his own hands, thus destroying her.

Spike climbed the tower where the ritual was to be performed in an attempt to rescue Dawn, but was outmaneuvered and thrown off the tower by one of Glory's followers. Despite all the Scoobies' best efforts, Dawn's blood had already been used to open the interdimensional portal by the time Buffy reached her atop the tower. Dawn offered to sacrifice herself in order to stop the ritual, but Buffy, who at that moment understood the meaning behind the First Slayer's message, chose instead to sacrifice herself for the good of the world. She lept into the portal her blood, which Dawn's had been modeled after, effectively closed the rift. Buffy's allies stood over her body and wept openly. She was buried on the outskirts of Sunnydale with the epitaph: "She saved the world. A lot." Finally able to rest, she ascended to heaven, where she apparently found peace.

Several months later, Buffy was resurrected by her friends who had feared that her spirit had been trapped in a hell dimension due to the mystical circumstances of her death. In reality, she had been allowed to move onto heaven, where she had apparently found peace and happiness.

After crawling from the depths of her own grave, Buffy aimlessly wandered the streets of Sunnydale before being found and taken back to her house by Dawn. Buffy was comforted by Spike, who had been serving as Dawn's protector and sitter in Buffy's absence and officially joined the Scooby Gang in Buffy's absence. Her transition back to life was very difficult; she experienced an overwhelming sense of loss after being as she put it ripped out of heaven and thrust back into a world of pain. She had to take back her duties as the Slayer, and deal with the everyday responsibilities of raising Dawn, working and paying bills. She attempted to keep the secret that she had been in heaven from her friends, not wanting them to share in her grief, and confided only in Spike, though the truth ultimately came out when she was under the influence of the demon Sweet. Buffy's depression worsened when Giles left Sunnydale and returned to England when she became overly dependent on him.

Struggling to feel alive and seeking someone who understood her, Buffy began a violent sexual relationship with Spike which left neither of them satisfied, keeping it secret from everyone but Tara out of fear of their reaction. What initiated the relationship was the fact that Spike could now hit her despite his chip still working. Buffy consulted with Tara on whether her resurrection changed who she is and thus no longer made her a human according to the chip. Tara discovered that the chip was merely confused due to her mystical resurrection, upsetting Buffy as it made her come to terms with the fact that her relationship with Spike was her own doing and not anything outside her control.

In order to deal with her increasing financial problems, Buffy started working at a local burger bar called the Doublemeat Palace, a job she found degrading and disturbingly mundane. With all of these problems, Buffy sank into severe depression and self-loathing.

Meanwhile, Willow, proceeding Buffy's resurrection, developed an addiction to magic and began to use it excessively, which Buffy, faced with her own problems, failed to notice and largely ignored at first, even when confronted with evidence by Anya and Xander. This climaxed when a spell cast by Willow went awry and erased all of the memories of the Scooby Gang; when the spell was ended, Tara dumped Willow, which immediately caused Willow's addiction to spiral out of control. Buffy finally became aware of the full extent of Willow's addiction when she and Amy Madison began making regular visits to Rack, a shady sorcery dealer, which only worsened Willow's condition. When Willow made another trip to Rack's place with Dawn in tow, the two were attacked by a demon that Willow unwittingly summoned during her high, and Willow's carelessness caused a car accident that left Dawn severely injured. Buffy and Spike arrived in time to save them and, despite being understandably furious with Willow, relented slightly when Willow desperately begged her for help. With Buffy's help, Willow renounced the usage of her magic altogether and was put on the road to recovery.

In contrast to the ruthless hell-god Buffy faced the year before, her newest "nemesises" consisted of her old nerdy classmates that formed a group called the "Trio", with the intent of committing crimes, obtaining women and eventually taking over Sunnydale. Seeing Buffy as a foil in their plans, they made it their top priority to take the Slayer out, proceeding with several, ongoing minor annoyances against her, though she never had any interest in directly stopping them. One of their games led to accidentally turning Buffy invisible. At first Buffy enjoyed this new power by tricking the mentality of a social worker that was unimpressed by Buffy's ability as Dawn's guardian, and by desperately going to Spike for sex. Upon learning that if she were to continue being invisible her molecule structure would break down, Buffy sought to stop the Trio and made herself visible, not wanting to die despite her current grime state of life. The Trio's scheme's finally reached breaking point when their leader, Warren Mears, accidentally killed his ex-girlfriend Katrina after a mystical date-rape attempt. With the use of Jonathan Levinson's magicks and Andrew Wells's demon summoning, he manipulated events to make Buffy think she killed Katrina. Convinced, Buffy was ready to confess to the police, although this was thwarted when Spike dumped the body to save her. In an encounter of grief and denial in her relationship with Spike, Buffy beat him severely. Luckily for her, Buffy discovered that she wasn't actually the perpetrator of the crime and the death was ruled as a suicide; nonetheless, Buffy realized that the Trio were becoming too dangerous for her to ignore and resolved to bring them to justice.

Buffy soon met Riley again when she enlisted her help with a demon he's tracking. Buffy discovered that his current situation was much desirable than her own; Riley as happily married now while Buffy was desperately turning to Spike for relief. This realization shocked Buffy into finally breaking up with Spike, admitting to him that she was just using him and it was killing her. Confused and angry, Spike later got drunk with Anya, who had recently been left at the altar by Xander, and the two had sex in the Magic Box, which the Scoobies discovered through hidden cameras that the Trio had planted in the Bronze, the Magic Box, and Buffy's house. Xander subsequently attempted to kill Spike in a jealous rage, but Buffy intervened, revealing her secret relationship with Spike in the process; though Willow, Dawn, and Anya accepted it with relative grace, understanding what Buffy had been going through, Xander reacted exactly as Buffy feared, though he eventually realized why Buffy had kept it secret and apologized. Later, Spike cornered her in her bathroom, and in a misguided attempt to force her to admit her love for him, tried to rape her. She managed to fight him off, and in tears, dared him to ask again why she couldn't love him. Frustrated with his own inability to be either a man or a monster and disgusted with himself for his own actions, Spike fled Sunnydale.

After yet again foiling the Trio's plan, an enraged and embarrassed Warren tried to kill Buffy by shooting at her while she was caught off-guard in her backyard. Buffy used the split-second she had after being made aware of Warren's presence to push Xander out of the way and take the bullet in the process. Meanwhile, one of Warren's stray bullets accidentally killed Tara. Willow, enraged and grief-stricken, suffered a relapse and recklessly absorbed a large amount of dark magic. Willow saved Buffy at the hospital by telekinetically removing the bullet before proceeding to hunt down Warren and exacting bloody revenge against him; Willow flaying him alive before the eyes of her friends who came to stop her. Despite Warren's actions, Buffy was adamant that Willow had done the wrong thing and worked to protect Andrew and Jonathan (who had no involvement in Tara's murder) to prevent further deaths and to prevent her friend from becoming completely evil. Buffy even battled her best friend one-on-one so that the remaining Trio members could escape, but was promptly defeated before Giles came to her rescue. In the ensuing battle, the Magic Box was destroyed and Willow tried to kill Andrew and Jonathan with a homing fireball which Buffy managed to stop, though this resulted in Dawn and herself being trapped underground in the cemetery where the fireball impacted.

Willow then tried to destroy the whole world to end everybody's pain, which caused a number of demons to spawn and attack Buffy and Dawn. Xander eventually got through to Willow in the end. The trauma of Tara's death, Willow nearly destroying the world and seeing Dawn's proficiency with a sword was all it took to finally help Buffy out of her depression and caused her to realize that life was worth living after all. With that, she promised to stop her self-destructive behavior in order to be there for Dawn; with this crisis resolved, Buffy was finally ready to live again.

When Dawn enrolled in the recently rebuilt Sunnydale High as a freshman, Buffy was offered a job as guidance counselor by Principal Robin Wood, which she gratefully accepted. Initially, she found it to be an unfulfilling experience, as she was unable to connect with any of the students that came to her for advice, while others had trivial reasons. She soon became concerned when a girl with psychic powers, Cassie Newton, came to her claiming she would soon die. Buffy at first thought she was suicidal, but after learning it was an upcoming event, she saved her from being sacrificed by a group of demon-worshiping students. Afterwards, Buffy discovered it was actually because of a congenital heart condition that Cassie would die from. Cassie would be the first of numerous young women Buffy wouldn't be able to save in the following months.

Meanwhile, Buffy had discovered that Spike was living in the basement of the high school. Though at first taken aback by his madness, she eventually came to realize that he had regained his soul in order to prove himself to her. Recognizing that he had changed, she brought him out of the basement and helped him to recover. It eventually became apparent that he was being controlled by an evil force to feed on, kill and sire humans in town. Buffy tied Spike to a chair in order to prohibit him from moving; after he frenzied and attacked Andrew Wells, she chained him in her basement. When he begged her to kill him, she refused, and expressed her belief in him. He was later kidnapped by the agents of The First Evil. The First's minions had been tracking down and killingPotential Slayers in an attempt to abolish the entire Slayer chain. These Potentials were brought to Sunnydale for protection and training at Buffy's home; the house was quickly overrun with teenage Potentials.

Andrew, who had been under the influence of the First and captured by Buffy and her friends, led them to the First's area of focus, the Seal of Danzalthar, situated on the gateway to the Hellmouth; Spike's blood had been used to open the Seal. Upon investigating the creature that had been released, Buffy encountered an ancient and powerful vampire known as a Turok-Han. Buffy eventually stepped up as leader to the Potentials, and killed the Turok-Han to prove her determination and ability. Afterward, she delved into the First's lair, where she rescued Spike, who had been brutally tortured by both the First and the Turok-Han.

She later used the Slayer Emergency Kit given to her by Robin, whose mother was a Slayer herself. She used this to contact the the Shadow Men for assistance. In response they took her into another dimension and offered to increase her strength via the essence of a demon. Buffy refused, unwilling to sacrifice her humanity in exchange for power.

Meanwhile, a reformed Faith, having escaped from prison to help Angel, traveled to Sunnydale to aid the Scoobies in the battle. Upon learning that the First's minion Caleb had something of hers, Buffy led the Potentials into battle at a Vineyard to retrieve it, which resulted in the loss of several girls as well as Xander's eye. With this, the Scoobies and Potentials, having been losing confidence in Buffy's leadership skills and methods for quite some time, held a mutiny, appointing a reluctant Faith their leader and forcing Buffy out of the house. Alone, she briefly resided in a house that had been abandoned by its owner.

Only Spike remained loyal to her; he followed her to the house, and expressed his love and admiration for her; it was because of his belief in her that Buffy was able to overcome her feelings of rejection and depression, and found the strength to keep fighting. Through quick maneuvers and witty remarks, Buffy found the object Caleb was keeping from her an ancient Slayer Scythe and saved the Potentials and Faith after the latter led them into a trap, earning back the gang's loyalty and finally making peace with Faith before revealing her plan to share her power with the other Potentials.

Also, with the help of Angel, Buffy finally defeated Caleb and killed him by cutting him in half, killing the First's leading enforcer and one of her greatest foes. The First confronted her once more. From the rantings on how there was only one Slayer, Buffy realized her revolutionary idea.

Willow used the Scythe to perform a spell that activated Slayers all around the world. This happened just as Buffy led a