R.A.B (Regulus Arcturus Black) was killed by his realization of what kind of man Lord Voldemort was. He was killed by his bravery and his determination to swap the real Horcrux with a fake one so...
RAB is Regulus Arcturus Black. He's younger brother of Sirius Black. He stole The Slytherin's Locket and ordered Kreacher to destroy it who failed miserably. Then locket was stolen by Mundungus and...