It's been a while since I played but it is one of the last things you do in season one if I recall. As for the sis the story is centered around her and she is shoved down your throat whether you like it or not. I'm in it for the incest so I don't mind it so much even though if I had a choice it would be the cousin. But it bothers others, like yourself I assume. Whether or not you play without the patch she is like D or Melody so there is no avoiding her. But unlike the other two I don't really care for her myself.