Myne and Aaron basically form a family with him after the thing with the heavenly dragon is settled. Myne becomes his big sister figure and Aaron legally adopts Fate and makes him the successor to his house of holy knights.
The bad one is where he killed one of the holy knight siblings who he worked for while uncovering a plot to kill Roxy and destroy her house. The good one was when he was hired to protect his home village that he was chased out of when his father died. The one who hired him, the village chef's son, was the leader of the kids who bullied him. He has his own kid now and has grown to remind Fate of his own father. Though the other villagers didn't reflect after kicking him out so they didn't have to support him and remained "poor in wealth and heart" this father did become a better person. Since Fate could only protect a few, most of the village was destroyed but this wasn't portrayed as satisfying. They're suffering didn't make anyone feel better and it just felt strange and bitter to him.
He finds similarity between himself and the eldest sibling who was actually lashing out because of the things his father did to him and his mother. Aaron and the others were getting concerned because he becomes so aggressive when dealing with corrupt holy knights. He reflects and stops letting his anger get the better of him, lest he succumb to the sin skill or the "Area of E".
The stat cap is suppose to be 999999999. Beyond that is the "Area of E" which normally can't be reached. The fact that those in the Area of E can't be hurt by anyone who isn't or that E stats are just the multiple of the cap you have in stats might seem to reinforce the importance of stats in the story but it actually points out a problem with stats, control and expression. As he learns from Aaron and his match with Roxy, he needs to develop actual control over the power to express it. Otherwise, the impact of his stats is actually pretty small. There is also the problem of maintaining ones sense of self. Those who break into the Area of E (either through a sin skill, breaking their limit like Aaron, or whatever the white knights did) lose their mind and turn into monsters like the heavenly dragon if they can't control that power. Anyway, as he learns more and he, Aaron, and pretty much anyone who stays relevant in fights (sorry Roxy) go into the Area of E, the fights will address stats less and less. The fights will go more into the skills and their knowledge of how to use them.