User's shadow reflects how they feel

Pros:
-shadow can protect user
-user is the only one who can touch shadow
-user can control shadow if needed
-user can talk to shadow in unique language
-shadow can aid user

Cons:
-shadow is likely to be very VERY annoying at times
-user can't stop shadow morphing
-user's control is weak at the best of times
-shadow is the opposite of user at times
-shadow can mess with other shadows

Weakness: injuries
If the shadow or user is hurt, the other is too