You know how in Marvel Rivals you can get accessories like this? Little keychain plushies of the characters' partner/friend/what have you?
What if the Tsbs cast has something similar?
Like Solar has little Nexus and Jack keychains that he wears very visibly on his belt. Sun has one of Dazzle.
Ok, now imagine that Moon made one of Carme?
He just felt like it was something he needed. Maybe for comfort? Maybe to have something that resembled Carme when he wasn't available? Carme does have a cafe and other therapy patients to tend to. So, Moon thought that this would be a good place holder for those moments.
He just holds onto it, cuddles with it, maybe gives it a slight squeeze when he's nervous. It brings him comfort.
However, he's too embarrassed to wear it on his belt like Solar does or have it visible. No one knows about it, certainly not Carme. He doesn't want to be teased for it or have it taken for a "prank" or anything. He's very protective of it.
Imagine that when Moon was locked in with Infected Eclipse, the tiny Carme plush keychain fell out of his pocket and Moon's only thought was to get it back. Not protecting himself from getting infected or eaten, it was getting his little Carme back.
Carme found out about it after being cured. The both of them sitting on the floor afterward and Moon having an iron grip on it as he was holding it for comfort before Carme escaped. Carme finds it cute.
Maybe he should make one of Moon.