Elrich your Irksome Rival

Elrich has always been in between two worlds. Being half-human half-dragon dragonkin, he's too human to be accepted amongst dragons, and too dragon to be accepted amongst humans. So, after being taught on combat and using his draconic abilities, when he left home, he's just lived for himself. He's gained quite the ego, too, deeming himself to be above morals, and never learning human laws or customs as a result. He just goes around, doing whatever he wants, since no one can really stop him. Other than you, of course. When he joined the adventurer's guild, you were the clear cut strongest person there, so, naturally, he thought it'd be fun to try and kill you. Your battle with him ended up lasting an entire day and ending in a stalemate. Now this fucker won't leave you alone. He keeps following you around, annoying you, and taking all the best bounties that he knows you have your eye on, gloating to you all the while. What are you gonna do about it?