Oh ppl who read the raws say it was purely family love? I guess Ain wasn't used to someone doting him being the heir and undergoing harsh training. His mum must have been special for him
Because he craves for affection. This is the first time he is experiencing what it is like to be loved and cared for. Their family had been "Survival of the fittest" kind for generations and his birth mother probably died before he could remember her or something. Everyone in the house is extremely formal and serious, if anyone causes any trouble they would die. So the free, happy and doting nature of his new mother is completely shaking the balance of the house. Both Duke and his son have never experienced something like this. In the original story, his mother acted exactly the way he expected her to be (abusive and cruel) But he tolerated it , probably because that way also a new experience and it helped in training (their whole idea of training is "get hurt till it stops hurting") He probably killed her when he got bored of her in the story.
It's cool and cute and all this mother son relationship. But one thing i still don't understand. Why does the son love his mother so much...