I hope this kid is alive, and they figure out what his motives were. There are a couple points hinting at the brother being an extremist (youtube subscriptions) and possibly hot headed (domestic violence). Even his uncle called him an idiot. The younger brother, though, is described as a typical college student, fairly friendly, and even a person who went out his way to help others. It's just so odd. The other thing is the older brother actually tried to hide his identity at the Marathon. The younger brother went in with his hat backwards, eyes uncovered.