I've been looking at some of the theories around 'He is Mar' and the only think I could think of is that RJ is facially disfigured or deformed in some way eg he has a missing arm which would set him apart.

1. mar - a mark or flaw that spoils the appearance of something (especially on a person's body); "a facial blemish"
blemish, defect
2. mar - destroy or injure severely; "mutilated bodies"
mutilate, maim - injure or wound seriously and leave permanent disfiguration or mutilation; "people were maimed by the explosion"