The Mage King Is Back

David is despised by everyone around him. His fiancée does not love him and never did, and his own family treats him as a joke. The occasion where this is meant to play out again is the birthday party for his fiancée's grandfather, where the whole room is waiting for him to be humiliated once more. The David in that room is not the same man. Roy was the greatest Archmage in the magical world and died saving his realm, then woke up in David's body, carrying his own memories and his own power. It is through those memories that David learns what his fiancée and his family actually think of him. At the party he fights back for the first time.