I don't think he turned into a saint. He's still the same guy he used to be but now that the archer lost weight and looks (conventionally) attractive he treats him better.
He felt sorry for him when he was still overweight but was disgusted when he confessed because of the way he looks. But he looks desirable to him now and that's why he treats him nicely. If the archer was still fat he would react the same way he did back then.
yeah i was just angry, i binged this in a day lol and when the archer's hand was injured, he hoped that he won't be able to play anymore that way he'll stay with him forever... -_-
tbh the story with the archer and the narcissistic guy still doesn't make sense to me... like the dude suddenly became a saint after calling someone an animal for being fat? i don't understand and red-haired guy deserves better