A great way to introduce the hero, villain(s), secondary characters, and stock characters is to invite them all to a party as part of your book. While not every story is well-suited to throwing a party, I think you'll find that only the most strait-laced, strict, or unusual of settings would absolutely forbid any prospect of a party.
Whether your characters are attending a dance, having drinks at the governor's mansion, or playing video games during a sleepover, there are many possibilities for exploring your characters' reactions in this less serious environment.
Finish the party sequence prompts above, adding in things like:
A) Whether the hero and villain would fight each other even though everyone else just wants to enjoy the party,
B) Whether the hero enjoys the party or spends the night avoiding an angry ex-girlfriend or ex-boyfriend, or
C) If the party comes to an abrupt halt, what caused it? Earthquake? Magical portal opening? Someone called the cops to complain about the noise?
Use your imagination, and have fun writing!