Ahahah... oh, ok, I think I got it :D
SPOILERS BELOW, you are warned :)
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So, MC is actualy ancestor of fire goddess from the mother's side and son of the warlock/necromancer from father's side. Interesting, maybe we will have a possibility to use one or two dark magic spells (maybe even it could be possible to decide during battles with erassers to use fire or darkness). But what more interesting - his father have a daughter with dark magic powers on the side. Aaaand what do we have here? Ok, no need to play aroud, my guess is that Alice is MC's sister :D
She told that her family are ordinary people (yeah, a warlock that is born in ordinary family, ofcourse)... but also told, that her father always considered her as not his daughter. Sooo... Im sure on 99% that my gues is right :D
I definetely want to see continuation of this arc in the next update :)