"He knows he suffers in some way from depression and SADs"
out of everything you typed, this caught my attention.
we who have depression don't have to suffer from depression.
has he talked to his doctor ir a psychologist about this?
there could be an underlying psychological disorder that a psychologist can determine.
saying you feel youre dealing with 2 different people at times and some of the other things you describe has me thinking there could be something deeper than just depression or SAD, which a psychologist/psychiatrist/therapist could help with.
HOWEVER
has he worked the steps of the program?