And you said that your character was going to be similiar to Alexander, though it seems as though you have gone through some revisions, though keep the whole lost archipelago but at the very least changed the name and dropped the life conduit ability. 

I thought Kaite and Alex were good foils, and that is still true, but Mikeal is the antithesis of Alex. And unless you want to tell me otherwise, I am going to presume that deamons and their magics are similiar enough to demons that Alex's magic would burn him and weaken his magic and abilities, though it wouldn't react as strongly as if were demonic magic. 

To clarify, while I think it is safe to say that life magic innately has a strong negative reaction when interacting with death (necrotic) magic, raw life magic might have some negative effect when it encounters demonic magic, but with his rebuke darkness, it is him specifically channeling the energy and altering it in such a way that it will disrupt demonic energy. And other than the fact that demons bad, there is a reason why he would specifically learn to disrupt demonic influence, and it is as part of his standard training in Rutan magicks, and is as spiritual as it is practical. Though, Alex wouldn't know the reason, other than well, demons bad and I was told to learn this.