This is, hands down, my all time favorite season of Buffy!
We start off with the beginning of the end of Buffy and Riley. First Dracula comes to town and Riley has to wrestle with his Buffy insecurities as he watches Buffy fall under Dracula's spell. Buffy ultimately defeats Dracula but all Riley can do is draw parallels to Angel. Then Xander moves out of his parent's basement. While Buffy and Riley help him pack, Riley confesses to Xander that he knows Buffy does not love him. This is followed by Riley falling ill from the Initiative experiments on him. Buffy worries for him, but Riley refuses to seek out help - in part because of fear of what the government will do to him next and in part of fear of being Buffy's "normal" boyfriend. This causes fighting between them. In the end Buffy reaches out to the Initiative and it is revealed that Graham has been in contact with Riley, trying to convince him to accept their help. Riley does have the operation in the end, saving his life, but it doesn't help that Graham rubs in just how normal Riley is in comparison to Buffy. It also doesn't help that Spike has been rubbing in the same comments, or that Dawn slips up that Buffy doesn't want Riley patrolling anymore because he is now weaker. And while Riley is going through all of his problems Joyce starts to fall ill, causing Buffy to pull away from Riley to focus on her family. Riley does have a champion in Xander, who tries to drop hints to Buffy about how unhappy Riley is, but his hints go over Buffy's head.
Then there are the minor notes that Spike begins to realize he has fallen in love with Buffy. Giles decides to leave Buffy's life only for her to ask him to be her Watcher again. Still looking for some direction in his life, Giles decides to run the Magic Shop. And Tara struggles with still feeling like an outsider in the group.
But most importantly is the introduction of Dawn. The season starts with the fight against Dracula, but at the end of that episode Buffy walks into her room to find a stranger and demands to know who she is and what she is doing there. Then Joyce refers to her as Buffy's sister and from this moment forward the magic is cemented and everyone believes Dawn is a constant fixture in their lives. Joyce has a moment where she sees through the magic when she falls ill and passes out, but once she comes to she is back to believing Dawn is her daughter. Buffy rapidly finds out the truth as she searches for a reason for her mom's sickness. When she finds out she is furious that monks rewrote her life and her memories - along with everyone else's. But when she tells Giles the truth she comes to realize just how innocent and helpless Dawn is, and just how much she needs to protect her. Buffy and Giles decide to keep the truth to themselves for now and Buffy goes home - to care for her sick mom AND comfort her scared sister.
My favorite episode is "No Place Like Home." Buffy discovering the truth about Dawn and deciding it doesn't matter, she will protect her - both from the forces of evil that seek to use her and from the truth of her birth - no matter what, is exactly why Buffy is the hero.
The episodes:
Buffy vs Dracula - Season 5, Episode 1
Synopsis - Dracula comes to town, looking to seduce Buffy. Dawn enters Buffy's life.
Real Me - Season 5, Episode 2
Synopsis - Life from Dawn's point of view as Harmony tries to kill Buffy.
The Replacement - Season 5, Episode 3
Synopsis - A Toth demon tries to use a weapon on Buffy but accidentally uses it on Xander instead, separating him into Xander's good qualities and bad qualities.
Out of My Mind - Season 5, Episode 4
Synopsis - Buffy's mom falls ill, Riley is dying from the government experiments preformed on him, and Spike discovers a way to get the chip out of his head.
No Place Like Home - Season 5, Episode 5
Synopsis - Buffy starts to think her mom's illness might have a supernatural origin, but in search for answers she instead discovers that Dawn isn't actually her sister.