Based off of this

Here's the story down below (copied and pasted off of the internet with changes to fit the video here)

A "circus" would kidnap children, amputate them, r*pe them, throw acid on them if they misbehaved, and make them act cheerful and happy for visitors who came to see the "show". To see the show, you had to look through holes in various tents

Kyle is now a "deformed diva", having her legs replaced with that of a goat. He also may be blind due to acid
Wendy and Stan have both of their heads on one body.
Tweek had his brain switched with a dog's and is hinted to be a cannibal.
Cartman and Butters had their legs extended to become as tall as they can be, with Butters having to be Marjorine
Craig has either committed suicide or died because of the acid(thus the flowers on him)
They all hate the circus, although Wendy pretends that she is happy and having fun while Stan and Kyle openly express their hatred for it.

Flowers represent the acid that has been thrown onto their bodies.

Kenny also joins the circus but I am not sure as to what his role is.

Anyways onto thr ocs, your oc can be someone who visits the circus to be captured or is already a "performer" there

Alisa Thornson
She is a child who visits the circus

Kaylie Broflovski
She is known as the delicate fairy. Having wings  sewn onto her back. She does not like to be stared at and will hide behind any of the other "preformers", at least who is near her at the time. She can see, hear and talk perfectly fine but she has stage fright. She can be seen talking to either Kyle or Tweek, well she tries to talk to Tweek.
Her wings

Or

Her outfit

But the veil covers more of her face and is pretty thick, but she can see fine from the inside, just people cannot see her face

Andy Tucker
He is the deaf cat neko. His hearing went away as the surgery he had to get thr cat eats and tail had destroyed his hearing due to things being too noisy. He also self harms himself with his claws. He's mostly gone off the deep end and wants to be killed badly
Now he wears a pastel green oversized sweater with boxers underneath, having a fluffy blond cat tail and ears to match, having his nails grown out to be claws.

Lexi Solar
They are also a child who visits the circus