Innocence
Buffy watched as Dawn climbed the stairs. There was so much the girl didn't know about who and what she was. Part of her wanted to tell Dawn everything, be honest with her. But she knew she had to keep the information from her sister, to protect her from the truth.
No one would be safe if Dawn knew. It was too much of a risk. For now, Dawn had to remain innocent. Buffy was the Slayer, protector of the world from everything that went bump in the night. She glanced around before following her sister upstairs to bed.