side-kick
ally
advocate
supporter
bystander
helper
assistant
friend
pal
mate
coworker
team mate
A person who looks on the gloomy side of things is pessimistic.
flip side?
An optimist.
An optimist.
Multiplayer ?
Optimist/optimistic
An optimist.
A deserter - or turncoat.
pessimist
partisan
A Medium
in the side there should be a slot, if not call a computer person