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 her bedroom, "Little sis coming, I know."
According to Buffy creator Joss Whedon, the introduction of Dawn in Season Five was partly so protagonist Buffy Summers could experience a "really important, intense emotional relationship" with someone other than a boyfriend.