It just I have this drawing idea for a while but can't draw yet.
I know Will's fears: Spiders and cold temperature. Cold can also hinder his monster powers. So he have to avoid Abbie most of the time. Even copying and absorbing her power is more a challenge than most Monsters.
Shapeshifter? You know, among the monsters (except Demons) in Supernatural, I find Shapeshifters are real psychopaths. Most monsters harm people for food, They harm people for cruel entertainment. I'm sure you remember the first Shapeshifter goes around framing people for no reasons. And don't forget that one Shapeshifter trying to be like the Classical Monsters from old monster movies.