Well.... What I said about posting soon..?? In my defence, I was busy with exams and everything.
So! Some Der's design and lore for my Au which I plan to develop more later!
(Feel free to point my mistakes, English is not my first language)
Basically, when Derek first saw King and was given Infinity Knowledge, he also absorbed King's will to find the vessel. Since then all Der's actions were unconsciously aimed to make Avery merge with The King.
When Derek pushed Avery from the edge into the void to save him he actually completed the ritual. However because of instability of ritual and some unnoticed flaws Avery wasn't fully consumed by The King, leaving just physical body for It. Their minds, souls and eventually personalities fused in one, creating strange mix of a Mad God and a regular human.
After transformation started, Derek suddenly understood what he had done but it was too late. Prince was born and Derek, affected by mixed Knowledge and his love for Avery, was full at His service. Prince adores his kind, gentle, smart and the most loyal Knight.
Unfortunately, Derek didn't walk out completely without any injuries (months of starvation and beef with an Eldrich God doing this with you), but he was glad he was alive at all. Before face of possible death light migraines and lack of nutrients were nothing.
Prince didn't want to take over the world and was glad to just enjoy simple human pleasures.
World domination can wait! Avery wants to make out sloppy style with this shitty looking boy kisser!