Abort on attempt to make Billy like me. It'll be like when your mother forces you to be friends with the geekiest kid in class, and you hate every minute of it. Trust me, as the geekiest kid in class I know the scenario. Have devised plan: Will poke him repeatedly, and eventually he'll realize I am not trying to kill him.
Do not, I repeat, do not let the happy people decorate for you. We'd have to be enemies forever then, you and I. You would miss me, and it would be tragic.
You can try to purchase the artwork yourself? I don't know if that would work, though. Simon's been really down lately, guilty over his brother's death, and more than a little freaked out by his newfound mutant sister.
Have the happy people corrupted you yet? I must know.