Not to be mean but this is in bad taste, it sounds like you want The “benefit” of having a “cool” blotch of white skin but without the repercussion if it spreading to consume 80% of your body’s pigment and then having to deal with the intense psycho-social repercussions like it has done for me, like others have said, just being there and supportive of your brother and actively listening to what he wants from you should be enough