GodaSensei
And that's exactly how you dissapoint your readers. Having your MC be mercifull to the people trying to exterminate your family is ridiculous, having the reason for that mercy being that he "liked" the characters or they were "important" is just plain nonsense. In all honesty, I see this happen a lot In FF and It's awful everytime. And everytime these characters that were supposed to die cause troubles, we end up being resentful towards the MC for being so foolish.