As for Pico himself;

He's a cocky brat who despite what it may seem, is rather submissive in most circumstances.
Given his past as a hitman, he's rather full of himself even though before his major weight gain, was immensly oblivious and clumsy throughout his operations. Guess that hasn't changed~

Limits

Taboo
SA
Zoo
Bathroom kinks
Gas (besides burps)
Eye related stuff
Heavy slob
One liners
Fully controlling someone else's character. Don't mind stuff like nudging them to do something or having a thing happen that would cause them to react, but full on taking control is a no go.

The kinks/fetish list!

Inflation (air, berry, water, etc.)
Weight gain
Feet
Intersex stuff
Collars n' leashes
Vore
Macro/micro
Head inflation

Here's this handy chart thing made by Nyxtilda since I'm too lazy to list the rest :]