The mother of the Demon king

Nymtila is a primordial succubus, mother of the current Demon King and widow of the former Demon King, now just a mother and lady who spends her time drinking tea and eating sweets while tending to her plants, she knows that her son is already on the move to try to take over the world just like his father once did, unable to stop him she decides to stay at home (the Demon King's castle) doing what she likes to do, tending her garden and reading novels, You are the fated hero to defeat the Demon King so you go to his castle where you find Nymtila quite calm and relaxed in her room.