I have a feeling Cleo would regress a LOT since they were 13 when they were thralled and never really finished having a childhood
At first it might've been involuntary and frightening and she might've not handled it in the best way at first (not really understanding what was happening) but once Pearl found out, she explained regression to Cleo and offered to be her caretaker. Cleo was nervous about regressing in front of someone since they'd always hide it before, but they trusted Pearl more than anyone so they agreed.
Over time she got more comfortable with it and by post canon (2006 I think was the date?) is comfortable regressing around Pearl, Shelby, Drift, and Scott
She's a very quiet little, always trying to stay out of the way even when Pearl tells her it's okay to take up space. Being curled up in a corner always feels more comfortable than running around.
If it's ever a full moon when Cleo is regressed they will insist upon cuddling with "big puppy Pearlie" at all times. It's unfair to expect her to resist when Pearl is just so adorable and fluffy like that
Oscar (their cat) loves when Cleo is little and can always tell, he'll stay close to them when they're regressed especially if Pearl isn't there and it's sudden
Little Cleo's favorite things to do with each of the people she regresses around:
Shelby - reading, she loves when Shelby reads stories to her
Drift - around Drift little Cleo gets very protective and still sees Drift as a fledgeling, (for example:
Cleo: You're just a newbie, I hafta protect you
Drift: Cleo I've been a vampire for hundreds of years
Cleo: Just a little fledgling!!! I hafta protect you cause I know more vampire stuff
Drift: But I'm- ugh, okay, fine. You're a very good protector
Scott - Cleo likes to argue with Scott in a playful way. They're never actually mad, just cranky and needs a way to express it. And banter with someone as witty as Scott helps with that
Woo, sorry that was long, I had a lot of those, lmao
i love these!! cleo deserves to be small and have the childhood they didn’t get :( their backstory makes me so sad, it’s horrible and they deserve all the love ❤️🩹
also her still being so protective over drift and still seeing her as a fledgling after so long and even when little is very cute