I think I wouldn't hunt the person down (because of my family issues) but I could see any normal, happy person hunting them down to avenge their family, and I think it's quite an interesting concept, and it'd be really neat to see the main character have an inner struggle of whether or not to use his powers (as they exist because of his family members' death) in scenarios where people close to the main character are in danger. 

Some happy things would be having comrades to help you through this inner struggle, and an interesting scenario would be if your comrades started out as people who hated and distrusted people with gifts, as they basically saw themselves as above everybody else and they're known to kill people they're attached to.

If you want scenarios you can think of how the general public would see people with gifts, how other people with gifts would see people with gifts. Would people with gifts be accepted into society? What does the government do about people with gifts since they're technically a treat to the public? Would mentally unstable individuals (like people with mania, who get ecstatic very easily) have stronger gifts? What do people use their gifts for? ( I think the last point is especially important, as it must be something important enough to kill loved ones over ) but yeah, just some things you can add to the story if you want! sorry if you stated it in your story paragraph but why does ace kill Duke's family? Does he see something in Duke?