A few thoughts that have become concrete
I've come up with a few definitive thoughts on Jesper:
Yarrow makes his clothing. Jesper does not care in the slightest about getting dirty, so he has a bunch of casual clothes he can muddy up.
His more intricate jester outfit is something he's seemed to have for awhile, but saves it for festivals or important things.
Jesper can levitate and teleport around, but this ability something he doesn't do very often and forgets about. It's something that he cannot do for long periods of time, or use to get very far.
Jesper has a habit of biting at his tail. Sometimes, he can be a little rough about it without realizing.
Jesper uses a lot of brain power to fight the impulse to be mischievous. He's generally good-natured, but loves to bite and lick others. (Tells himself "no bite... no lick!!!")
Cannot stop laughing very long and sometimes does so in his sleep.
Is very tactile and prefers to feel his way around with his eyes closed. Very rarely, he'll squint to gain some idea of where he is in relation to things. In pitch black, he will open his eyes.
Loves to be tucked into his sheets at night very tightly.
His owners weren't exactly great towards him since he wasn't found very helpful. I have to figure out more about how Yarrow came in possession of the bag that Jesper inhabits.
This is all very work in progress stuff, so I'll be back to update.