Warren Mears

Warren Mears was a mad scientist turned major enemy to Buffy and her friends, especially Willow - he was responsible for the death of Tara and Willow's descent into madness and changed from his origins as a comedic villain to that of an evil woman-hating psychopath.

Early life
Warren Mears grew up in Sunnydale, California. At school, he excelled in science and technology but was bullied by his peers, including a jock named Frankie. As a teenager, he attended Sunnydale High for a semester before moving to a tech college in Dutton. However, he continued to be plagued by loneliness, and began to apply his technological skills to solve the problem. Warren built an ideal robot girlfriend named April, who was programmed to love and obey him. He assumed that he would love her in return, but grew bored of how easy and predictable things were with her. Instead, he met and fell in love with Katrina Silber, a strong-minded girl in his engineering seminar, and the pair began dating. However, Warren was unable to bring himself to break up with April, so he went home for spring break without her, hoping that her batteries would run out.

April followed Warren and Katrina to Sunnydale, where she proceeded to question everyone she met about Warren's whereabouts. This caught the attention of the Scooby Gang including the Slayer, Buffy Summers. When April's behavior grew erratic and violent, Buffy tracked Warren down and confronted him. He explained that April must have been recharging her batteries somehow, and Buffy became concerned about the danger she posed. When Katrina told April that Warren was her boyfriend, the robot angrily attacked her; Buffy and Warren showed up just in time to save her life. Warren admitted to April that he didn't love her, and she reacted violently. As she and Buffy began to fight, Katrina realized that April was a robot and left Warren in disgust. He ran after her, leaving Buffy to deal with April, whose batteries finally ran out. Warren was later approached by the vampire Spike, who harbored a romantic obsession with Buffy. Spike forced Warren to build a robotic version of the Slayer for him to have sex with.

The Trio
Warren resurfaces in the Season 6 episode "Flooded" as part of the Nerd Trio, along with Jonathan and Andrew. The Trio are little more than a criminal group who strive to take over Sunnydale, though most of their plans revolve around neutralizing Buffy, who, as the Slayer, is the one thing standing in their way.

From the beginning, it is clear that Warren (unlike his more passive portrayal in Season 5) is the leader of the Trio, dominant over Jonathan and Andrew, as well as more willing than the other two nerds to take real risks and possibly do real harm to people.

Starting with the episode "Dead Things," Warren shows his true colors as a dangerous, misogynistic, and possibly psychopathic individual. When Katrina reappears, Warren uses an enslavement device to make her obey his will. When she resists the device, Warren attacks her and accidentally kills her. Unmoved, he hatches a scheme using demons that cause temporal disturbances to confuse Buffy into thinking she was responsible for Katrina's death. Buffy eventually figures it out, but Warren and the Trio evade her for the time being.

After Katrina's death, Jonathan becomes increasingly unhappy with Warren's lack of conscience. Warren plots with Andrew, who is enamored with him, to ditch Jonathan in the near future.

In "Seeing Red," Warren makes his bid for major villain status when he steals a pair of magical orbs which give him strength and invulnerability. He, Jonathan and Andrew attempt to rob an armored car, but Buffy arrives and the two get in a fight, during which it is clear that Warren's Orb-granted strength makes him more than a match for the Slayer, even taking the time to gloat that he has finally defeated the Slayer, something that many have tried (and failed) to accomplish. In the midst of the fight, Jonathan appears to attack Buffy, but in fact surreptitiously tells her how to defeat Warren. Just as Warren has Buffy at his mercy and is about to finish her off, Buffy sees the pouch containing the orbs and destroys them. As a contemptuous Buffy advances, an enraged and humiliated Warren escapes with a jet pack, vowing that he would take Buffy down, and also leaving Jonathan and Andrew to take the fall with the police.

The next day, Warren, furious at Buffy foiling all of his plans, appears in Buffy's back yard with a gun. He shoots, critically wounding Buffy and accidentally killing Tara with a stray bullet. This action causes Willow to descend into madness and threaten the world as "Dark Willow". Upon discovering that Buffy had survived his assassination attempt and that Willow was after him, Warren immediately traveled to the hideout of sorcery dealer Rack, who supplied him with protection spells. Unfortunately, these were not enough to stop Willow, who eventually hunted Warren down and tortured and flayed him alive through witchcraft.

Later Life
The First Evil appears as Warren a few times in Season 7 - including as Season 6's representative in the parade of villains at the end of "Lessons" using his appearance mainly as a means of bending Andrew to its will. Using this method, the First Evil gets Andrew to murder Jonathan (in "Conversations with Dead People"), in order to open the seal in the basement of the new Sunnydale High.

Warren's final major appearance occurs when a spell (cast by Amy) causes Willow, feeling guilty over moving on after Tara's death, to manifest her feelings by making her outwardly assume the appearance of her former victim. Later it appears that Willow's mind starts to become replaced by Warren's.

The real Warren, however, returns months after the destruction of Sunnydale. Having been saved from death by Amy, seconds before he could have been killed by Willow, Amy uses her magic to keep Warren "alive" despite his lack of skin. He was the one who gave Amy the idea of cursing Willow in order to become him, and he bears a considerable grudge against both Willow (for flaying him) and Buffy (for ruining all of his schemes).

Amy and Warren remained in the remnants of Sunnydale after the massive exodus and were present during the town's destruction. They remained for months in the crater, feeding on whatever edible substance they could find, until they were found by General Voll. In exchange for their aid against Buffy and the Slayers, Warren asked for a chance to exact revenge on Willow. In Part Four of "The Long Way Home", he reveals the means of his survival as he lobotomizes a captive Willow. When Buffy and Satsu arrive on a rescue mission, Amy teleports away, taking Warren with her. Willow heals instantaneously.

In Part 1 of "Time of Your Life", Twilight is seen with Warren and Amy in some sort of military base, where Warren shows him something that will help get Twilight's job done: a missile, which targets and destroys the Scotland castle headquarters, with Xander looking on nearby, helplessly. It seems Warren is still a technological genius.

In "Retreat", Part 1, while on the run from demons with his Italy squad, Andrew discovers a bleeding and skinless Warren underground who claims to have been abandoned by Amy to die slowly as his magical skin wears off. Andrew listens to Warren's pleading, and he seems to take responsibility for some of the First's claims while under Warren's guise, such as the instruction to kill Jonathan. However, it quickly transpires that this was a ruse as the goatmen demons descend and Andrew and his Slayers are forced to fight back and retreat to the Scotland Slayer Organization headquarters. Amy interrupted his ruse on purpose, believing it doomed to failure because it was the First who tempted Andrew before and Warren was "not the First."