Scar is a disturbed loner. His right arm does not belong to him, but his brother. His brother was obsessed with finding the Philosopher's Stone and tattooed his whole body. During the Ishval civil war...
Scar seeks his revenge against the state alchemists, all of whom he blames for the destruction of Ishval. His wrath does not extend, however, to non-state alchemists, which is why he does not seek to kill Alphonse Elric during their frequent confrontations.
