Actually this would this would be better as a town role. Need to protect the cop paint a target on a random blue head. Or Painter can claim knowing they can possibly survive by painting another. Have the doc save someone else because the maf can't kill a painted PR.

He needs to be sided with mafia

Hmm how about it is like the traitor and doesn't join mafia meetings. So it would be

*****
Paints a target on someones head.
Instead of the mafia killing who they want to kill they will kill the person with the target on their head.
Painter chooses who they want killed.
The painter can only paint a target once per game.
Painter is sided with the mafia and does not participate in mafia meetings.
*****

>If the target is mafia the target is not killed.

i'd remove this, and the it could be a powerful role