A demon Lord with brains for once. But I doubt the lead will convert to the demon side. Why should he. He wants nothing to do with either side and he has power comparable to a God.
not yet, in the wn they learn about it after the hero gave him the choice "serve me or go away"(guess what his choice is) and they have to use purification to stop the demonarmy which is sending killing intent.
If I'm remembering right, the demon king basically goes "Oh, I can't beat this guy" and then "Oh, this guy is a great guy" and they become best friends. At least that's what people have told me.
@Simkin
I wouldn't worry too much about it. It is a minor plot point at best. I dont think it really is ever mentioned again outside of a comment or 2. Also, it isnt like she is mad at him or anything. If you remember she even asked/expected him to kill her after she lost/ surrendered because she thought a worrier who lost was not needed in this world.
Half of it is likely pride based as well. And she likely comes from a place where losing/surrendering heavily damages your pride (a "there is shame in losing" kind of place). But she married the one who beat her, thus her pride actually went up significantly. Meaning no hard feelings. And her brother was defeated by the strongest, to them, I bet it is thought of as an honour.
@Simkin
I think she simply accept that it was just an accident from him getting the grasp of his power, it's not his intention, just an innocent collateral damage. Like you can't really blame someone for stepping on an ant when they are running in a hurry.