Spoiler maybe idk

One of my friend said he was friend with the main author and he told me one of their idea was actually: mc was the one who murdered his mother because of some mental issues like a split of personnality. At that time ml was in military and he was the one who discovered the massacre, ofc mc was already hurt because people tried to defend theirselves but still died so ml hit mc to make him faint. Years later ml found mc again and when he learned about his memory lost he decided to take him in because he felt that sorry for the kid. And when he told the mc he killed his mother by his own hand, it's because he decided to take the entire responsability of mc past action.
It was one of many ideas but I liked this one better! ╮(￣▽￣)╭