peach is pretty much lost god. when she gets to your office, she'll wait for you to look at the attic before entering (waluigi will wait for you to *not* be looking at the attic), and when she does enter, you need to turn the lamp's lights down. She'll leave faster when they're darker, leave slower if it's only a little dark, but she won't budge if you're also staring at the attic (this is to prevent you from trying to metagame her and waluigi).

TL;dr look at her and keep light off

She's pretty simple, and waluigi will be pretty simple as well, but that's the point for now. These two are merely meant to set the groundwork for more creative characters later on, so look forward to them...

for now i gotta also work on waluigi