Dude only knew he had a brother for the last ~2 years of his life, and those are spent trying to kill Elan. He was Elan's brother, yes, and Elan wanted to have some form of relationship with him, but theres no reason at all for him to snap, saying things like "you don't know what its like!" Especially when he doesn't know whether or not anyone else knows what it's like, and heel, ELAN barely knows what its like.