Dawn Summers first appeared in the season five episode "Buffy vs Dracula" and was presented as Buffy's little sister, which came as a shock for all fans. But there was more to Dawn than meets the eye. Dawn Summers was portrayed by Michelle Trachtenberg.

THE KEY
The arrival of Dawn Summers is foreshadowed in cryptic dream sequences in both the Season Three finale "Graduation Day, Part Two" and the Season Four episode "This Year's Girl," in which a still-comatose Faith says, while making a bed with Buffy in Dawn's future bedroom, "Little sis coming, I know." Buffy replies, "So much to do before she gets here." In the Season Four finale, "Restless," Tara warns Buffy to "be back before dawn."

In 2000, Czech monks of the Order of Dagon have possession of The Key, a mystical ball of energy that can open a portal to all dimensions. Once opened, the portal would create chaos on Earth as hell dimensions flood into this world until the energy is used up and the portal is closed again. The monks want to put this dangerous power to good use, but forces of darkness track them down. In an act of desperation, three surviving monks use powerful magic and part of Buffy to forge The Key into human form as a fourteen-year-old girl, and send it to the Slayer as a sister to protect from Glory, a hell-god bent on returning to the hell dimension from which she had been exiled for being too vicious.

SUNNYDALE
Dawn first appears at the end of the episode "Buffy vs. Dracula." When Buffy walks into her bedroom, preparing for a date at the movies, she finds Dawn looking through her stuff. Buffy's mother then suggests, "Buffy, if you're going out, why don't you take your sister?" and both Buffy and Dawn shout "Mom!" This is surprising as no mention of Buffy having a sibling had ever been made previously in the show. In fact, in both "Faith, Hope & Trick" and "Living Conditions", it is explicitly stated that Buffy is an only child. Dawn is supposedly born to Hank and Joyce Summers in 1986 in Los Angeles. Both Dawn herself, as well as her immediate family, are unaware of her mystical origin for a while, as they have been imbued with artificial memories of her as Buffy's younger sister. Only those "outside reality," such as mental patients, can see Dawn's true nature. Later, when Joyce develops a brain tumor, a brief moment of clarity allows her to see that Dawn is different.

Dawn instantly graduates to series regular in her second episode "Real Me", remaining in the show for the next three seasons and all 66 episodes. Her existence is further complicated by the fact that the writers do not acknowledge the strangeness of the situation for several episodes. Instead, she is implied to have strong relationships with Buffy and her friends, having supposedly known since moving to Sunnydale with her family at the age of ten. "Real Me" grants Dawn the position of narrator, introducing her personality and showcases her relationships with the other characters. She is portrayed as a rather klutzy, but otherwise normal teenager, who enjoys school and looks up to Buffy and her friends. However, the episode ends with Dawn somewhat ominously stating in her diary, "She still thinks I'm little Miss Nobody. Just her dumb little sister. Boy, is she in for a surprise."

Over the course of Season Five, Dawn and the Scooby Gang must first discover, and then come to terms with, how she came into existence. Upon learning of her mystical origin, she begins self-harming and runs away from home, but Buffy manages to assure her that they are real sisters no matter what. Dawn is then subjected to more turmoil when her mother dies unexpectantly from a brain aneurysm, almost resorting to necromancy to bring Joyce back from the grave. When Glory "brain-sucks" Tara Maclay, leaving her completely insane, Dawn blames herself, describing herself as a "lightning rod" for pain. As Glory's plan comes to fruition and the barriers between dimensions begin to crack, Dawn is willing to give her life to save the world, but Buffy stops her and sacrifices herself instead.

Season Six sees Dawn struggle with abandonment issues, as well as her escalating kleptomania. Having been devastated by her sister's death, Dawn is overjoyed when Willow casts a spell to bring her back to life. She later experiences her first kiss with a vampire named Justin, who she is reluctantly forced to stake when he tried to kill her. Feeling isolated from the other Scoobies, Dawn inadvertently makes a wish to the vengeance demon Halfrek which results in them becoming trapped inside the Summers house. When Tara is shot by Warren Mears, Dawn is noticeably affected by her death, even advocating Willow's decision to take revenge. Consumed by black magic, Willow tries to turn Dawn back into energy just to put an end to her whining. While helping Buffy battle demons, Dawn proves herself to be capable in a fight, finally earning Buffy's respect.

In Season Seven, Dawn learns how to be a grown-up and becomes a fully-fledged Scooby member. Falling victim to a love spell in the episode Him, she displays dangerous behaviour such as attacking people and even trying to commit suicide to prove her "love" for classmate RJ Brooks. While home alone one night, Dawn is forced to perform a solo exorcism to protect what she believes to be her mother from a demon. After wrongly believing herself to be a Potential Slayer, Xander explains to Dawn that being normal is perhaps the hardest burden of all, as nobody understands the pain of being overlooked. In the final battle against the First in "Chosen", she proves herself once again to be a strong and capable young woman, keeping a clear head and slaying at least three Turok-Han vampires independently.

Dawn was originally intended to appear in the Angel episode "The Girl in Question." However, Michelle Trachtenberg was unavailable for filming, so the character of Andrew Wells, played by Tom Lenk, replaced her.

AS A GIANT
In "The Long Way Home," Dawn has becomes a giant, which Buffy believes is the result of losing her virginity to a "thricewise" named Kenny. Xander, however, believes that she may have subconsciously brought it on herself as a way of gaining Buffy's attention after so many new Slayers moved in with them. Dawn's relationship with her sister is strained; Buffy says in a monologue that they haven't really gotten along since they "changed the world" in "Chosen." Dawn does not want to speak with Buffy about her condition, preferring to wait for Willow, who Dawn describes as "like a mom to me." Dawn has indicated that she wants to leave Scotland once her condition is back to normal, possibly to go to Berkeley, which is where Buffy wants Dawn to go to school. Dawn begins to accept the advantages of being super-sized when she stomps on malevolent witch Amy Madison, knocking her unconscious and allowing Willow to capture her.

Dawn is a human being who, as the mentally unstable can see, is really a green ball of energy. With the right ritual, her blood opens a dimensional portal to all universes, bringing chaos and destruction to Earth within minutes.

Dawn's experience in battling vampires and demons has made her a more capable fighter and spellcaster with the ability to cast spells from memory. She can also read a variety of languages ranging from Turkish to Latin. Dawn has grown to rarely flinch when in danger, and her loyalty to her sister and friends is absolute.

In Season Eight, Dawn grows to the size of a giant, possibly the result of losing her virginity to a "thricewise", an event which becomes a recurring gag in the series. However, she is not as proportionally strong as she is large, as mentioned by Buffy. Nevertheless, she still takes an active role in large scale battles, decommissioning enemies with super-sized kicks. She is shown to be able to damage a large stone wall by punching it, although she hurts her hand in the process.

ROMANTIC RELATIONSHIPS

Xander Harris — Dawn harbors a crush on Xander into her adolescence, feeling that he is the only one who treats her like an adult. Xander is both well-aware of and very flattered by her crush, exhibiting notable jealousy when Buffy informs him that she has moved on to Spike. Although she eventually outgrows her romantic feelings for him, Dawn and Xander remain extremely close, bonding over the fact that neither has any real "superpowers" ("Potential"). While living in Scotland, Xander is the only one insightful enough to conclude that Dawn may have become a giant intentionally.

Spike — Feeling isolated after discovering she is the Key, Dawn develops a crush on Spike because "he's got cool hair, and he wears cool leather coats and stuff. And he doesn't treat me like an alien" ("Crush"). However, she soon realises that he loves Buffy and accepts that nothing will happen between them, coming to regard him as a kind of 'older brother' figure instead. Spike has affection for Dawn; calling her "niblet" and often referring to her as "his little bit" and acting as her guardian in Buffy's absence.

Kevin — Dawn adores this shy boy in her junior high art class. He was surprisingly sensitive about her "family problems", indicating that he too had resorted to self-harm on occasion ("The Body").

Justin — A manipulative, teenage vampire with whom Dawn, unaware of his identity, shares her first kiss. When Justin tries to turn her into a vampire, Dawn is forced to stake him with a loose crossbow bolt, an experience which upsets her greatly ("All the Way").

RJ Brooks — Dawn develops an obsessive crush on this popular high school athlete due to his bewitched letterman jacket, resulting in her humiliating herself at cheerleader tryouts and pushing his rival down a flight of stairs. When she finally comes to accept that she can never be with him, she decides to commit suicide by lying on a train track to prove her "love" for him. Buffy rescues her, and the spell is broken ("Him")

Kenny — Dawn dated this boy for some time, although Buffy, Leah and Giles warned her that he was a "Thricewise." He apparently disappeared after Dawn grew to giant size, which Buffy believes to be a side-effect of losing her virginity. It is unknown if they are still dating ("The Long Way Home").


OTHER

Willow Rosenberg — Dawn always admired Willow; in "Real Me", she states, "Willow's the awesomest person. She's the only one who likes school as much as me." When Buffy dies, Willow and Tara move into Buffy's house and act as guardians to Dawn. Their relationship suffers a blow when Willow, strung out on dark magic, gets Dawn into a car accident, but they soon make up. When Willow is kidnapped by Amy and Warren in "The Long Way Home", a furious Dawn tells Buffy that Willow is "like a mom" to her.

Tara Maclay — Dawn befriends Tara early in Season Five, when even Buffy and Xander don't know her very well. At that point, neither of them are considered to be part of the Scooby Gang. Dawn was quick to defend Tara from her father in "Family", and was devastated when she was "brain-sucked" by Glory. Even after Willow and Tara broke up, Dawn and Tara continued to meet up for the occasional milkshake. Dawn was deeply affected by Tara's death, finding the courage to voice her opinion of what Warren deserved.

Anya Jenkins — Dawn was initially unfriendly towards Anya, no doubt jealous of her relationship with Xander. However, as time when on, they became closer, despite the fact that Anya often spoke to Dawn as if she were much younger than she actually is.