Henry is the drug dealer adoptive brother from his childhood who tried to make him run drugs. He beat Shin, then was beaten and shot himself. And shin saw him die and decided to do nothing about it. Austin is fairly at the beginning, a gay guy who he worked with in a garage. The slept together but Austin has sexual preferences that lead to I think an accident and Shin refused to go on. Austin's family then made no garage in the state hire him and gave him a bad reputation. The reason why Shin is fixing cars illegally on the streets in the beginning of the story. Don't know the chapter, but hope this helps :D
Ch. 7
Yeah, it appears that Shin used his fists on the Austin guy when the guy tried to push his limits with Shin! You can see the guy passed out with blood on his face and chest and Shin standing at the foot of the bed with a clenched fist and blood dripping from it.
on which chapter were Austin and Henry mentioned ? I just remember them vaguely