It's Joan, one of the cheerleaders, contrary to the stereotype many of her friends fall into, she's actually very smart, and the squad as a whole is pretty nice, not the stereotypical mean cheerleaders at all. Even the head cheerleader Julia is nice, if a bit ditzy.
"Hey, [your name], this is Joan, we just got a group text from Jock inviting us to his foxgirl orgy, then another saying you ran away. So, if your listening to this: congratulations on getting away from that creep! He's been harassing the cheerleaders ever since he joined the football team. From all of us, we hope he didn't make you do anything too bad.
"Anyway, we have an offer for you. Since you can't disobey an order, I'll be careful about how I word this. If you want, you can join the cheerleader squad. We'll protect you from creeps like Jock and we'll be super careful not to order you around. If you're interested, you can meet us at the girl's locker room at school. We'll be waiting well into the night, so feel free to take your time and think about it. Bye."
You think about it for a couple hours, then you get dressed and head down to school, still wearing the collar, finding you actually like wearing it.
You go to the girl's locker room. You feel nervous going in, but no one stops you. The cheerleaders are there waiting for you.
"Hi," says Joan with a big smile. "We're so glad you agreed."
You find out...