At the end of the TV episode, one of the other Creeps hands Ricky a cookie to allow him to transform. He wouldn’t have needed to eat the cookie at all if he was already a Creep.
Creeps, in general, seem to have extremely servile personalities; they will mindlessly obey anyone (even a human) who they respect enough. At first this was Alpha Bitch Tasha, which explains why they followed her lead in bullying Ricky.
Then, the message in the paper made them follow Ricky instead. The message ordered all Creeps in no uncertain terms to call Ricky, but conspicuously avoided referring to Ricky himself as a Creep. When they met up with him they never saw him transform like they did, and they never asked him to.
Later, when they threatened to eat him, it was because he came across as too weak-willed to be worth following, *not* because they suspected he might be human. In fact they already knew he was human (or figured he probably was), but to a Creep’s mind there’s nothing inherently contradictory about having a commander who isn’t (yet) a Creep.
It also explains why the other kids became Ricky’s slaves when they got turned. Creeps just *need* someone to boss them around. This replaces the normal human desire to befriend others.
The only exception is Ricky himself, but that’s probably because he was such a social outcast beforehand that the Creep “group-think” doesn’t affect him as strongly. This makes him the natural leader of the Creeps after he transforms.
Iris was mostly just friends with Ricky and didn’t know the other kids very well. So if she *did* give in and become a Creep at the end, she likely would end up as Ricky’s *actual* second-in-command, the very same role she pretended to have earlier on.
The Creeps would have followed Tasha instead, but to some extent they were already doing exactly that. They would have leveraged their existing relationship with her in some way.
Maybe they would have framed Ricky and Iris as being the real creeps, and told Tasha that the seeds were an antidote that would prevent the two from turning all the other students into creeps. All she’d have to do is get the students to eat the seeds and she’d be a heroine. Tasha would have gone along with this plan because it would have made her even more popular.
By the time she realized the truth, she wouldn’t care, because now the whole school would be following her. Which is what she wanted all along.
