Fans of Buffy the Vampire Slayer, watched the first four seasons of the series, assuming Buffy was an only child. In season five, viewers were surprised to learn that Buffy had a younger sister named Dawn. It's revealed later that Dawn is actually "The Key" and was turned into human form and placed under the slayer's protection, disguised as her sister, in order to hide The Key from Glory, the God who needs it to destroy the world and open all the portals to hell.
Buffy takes on the role of sister very easily, and all of the ups and downs and fights that come with the relationship. Buffy loves Dawn, but like any sisterly relationship, it's not always happy or easy, and sometimes, Buffy falls short in her role as a sister.
Good: Took Care Of Dawn When Joyce Died
Dawn and Joyce had a very special relationship. Dawn being the youngest, her mother still babied her, despite her being a teenager and becoming a young adult.
When Joyce dies, Buffy is the one to break the news to Dawn in a devastating scene in one of the most heartbreaking episodes of the series. Once Joyce is gone, Buffy takes on the role of Dawn's caregiver and works really hard to ensure that Dawn has as normal a life as possible under the circumstances.
Not: Left Dawn Alone With Spike
When Buffy has to patrol or is facing a major battle with a new demon or force of darkness, she can't look after Dawn. A lot of times, Dawn gets in the way if she does tag along with Buffy on a mission and Buffy doesn't want to take any chances of having Dawn get caught up in a messy fight with a big bad.
Buffy has a lot of friends that are able to help her with Dawn, but frequently uses Spike as a babysitter. Given Spike's history of evil and his lust for Buffy, he probably isn't the best role model for her little sister to be spending so much time with.
Good: Teaches Dawn How To Fight For Herself
When Buffy realizes Dawn is getting older and she won't always be there to protect her, she starts empowering Dawn to fight for herself and even begins including her in the Scooby Gang's meetings.
Dawn is great with research and begins taking on Willow's previous bookwork role as the go-to for finding information on whatever new demon they're facing. Buffy also never misses an opportunity to remind Dawn that she's strong and can fight for herself if she ever has to.
Not: Kept Dawn's True Identity From Her
It doesn't take long for Buffy to discover what Dawn really is, where she came from, and why she ended up in Buffy's care. Buffy at first struggles with the information because the monks who sent Dawn to her, changed her memories to include Dawn, so Buffy would believe she really was her sister.
Buffy decides not to tell Dawn about her true identity, believing it would cause more harm than good, but Dawn finds out anyways and she's devastated by the information, making the whole situation even more traumatic than if Buffy had just been honest with her.
Good: Sacrifices Herself To Save Dawn And The World
Ultimately, Buffy is unable to keep Dawn safe. She succeeds in keeping her away from Glory, but another demon who has been looking forward to Glory's plans coming into fruition, finds Dawn tied at the opening of the portal and he releases Dawn's blood, opening the gates of hell.
Buffy gets to Dawn, but she's too late. Dawn tries to jump into the portal to close, but Buffy stops her, realizing the Dawn was made from Buffy's blood, Buffy knows she's able to close the portal with her blood and she sacrifices herself to save her sister.
Not: Doesn't Notice Dawn's Kleptomania
Dawn struggles to cope with Buffy's death and begins to act out in different ways. One way Dawn rebels is by stealing things. When Buffy is brought back from the dead, initially, Dawn and her friends are thrilled, but they also know that being brought back to life is a big adjustment for Buffy, and Buffy doesn't share her loved ones' enthusiasm about coming back.
Dawn continues acting out, but Buffy fails to notice because she's too overwhelmed by her own trauma and unable to see how it's affecting her little sister.
Good: Saves Dawn From Sweet
Dawn's bad stealing habit is brought to light when a demon named Sweet comes to town and forces everyone to sing and dance until the combust into flames. Sweet tries to take Dawn, thinking she is the one who summoned him because she's wearing his talisman around her neck.
Buffy will fight Sweet to the death if she has to, to prevent him from hurting Dawn. Dawn its that she stole the talisman and Xander its that he's the one who summoned Sweet, which clears things up and the resolution comes with little violence.
Not: Trusts Her With Dark Willow
Willow and Buffy are best friends, and Buffy trusts Willow with everything and loves her unconditionally. This gets Buffy and Dawn into a bit of trouble though when Willow starts experimenting more with magic and her powers becomes more like a drug addiction than a fun and helpful hobby.
Buffy lets Dawn go off with Willow on one of her magic adventures. Willow takes Dawn to a witch who feeds Willow power, it's a dangerous place, and Dawn is really scared to be there, which could have been avoided if Buffy had been paying more attention to her friend's addiction and her sister.
Good: Got A Job At Sunnydale High School
Buffy re how hard high school was and wants to help her sister however she can as she navigates the ups and downs of Sunnydale High School. Buffy decides to get a job as the school counselor.
Not only will she be able to help Dawn with the occasional mean teacher or class bully, but she can also watch over her and keep her safe from whatever dark forces are lurking in the school's hallways.
Not: Convinces Xander To Kidnap Dawn
As Buffy and all of the potential slayers prepare for the ultimate showdown with the first evil, Buffy's first priority is keeping Dawn safe and out of harm's way. What Buffy fails to realize is that Dawn is just as capable as the potential slayers of fighting back and wants to be an active participant in the fight.
Instead, Buffy ignores Dawn's wishes and convinces Xander to kidnap her and take her as far away from Sunnydale as possible. Of course, Dawn figures it out, fights Xander off, and manages to get back to Sunnydale in time to help her sister.