Kanda Yuu
For Kanda things are simple: he fights and he wins. There is no other way of life. No other choice. And it was fine for him. His curse was different than Allen's but still a curse – to live. No matter how many times his battered body is cut, slashed, pierced, crushed he doesn't die. He can't die. Not before he finds 'that person'.
So he keeps fighting akuma not caring about anything else. He didn't allow himself to care, to form bonds. However, bonds are always formed when you interact with someone. But he doesn't care. He can't care. Because caring only brings pain to him and to others. But why should he care about how others feel? He doesn't.
N/A: Yes this chapter is extra short. that's why I'll submit the next chapter now too.