Susan isn't even in this department, but he couldn't say no to going to a party. He's already played Twister a few times (and lost every one), eaten snacks, and visited the birthday rat, and now he's moved on to socializing. At first he only was talking to people who were actually trying to socialize, but when he sees Snake he decides he has to get him to participate too. Only his brother is allowed to be a wallflower at this party.

Luckily he hasn't seen his snakes, or has written them off as some sort of change or clothing choice rather than as actual snakes. Otherwise him approaching Snake may have turned out entirely differently than this. As it is, though, he approaches with a small smile, trying to not be too obnoxious - he wants him to join in the fun, not get scared away.

"Are you people-watching?"