He isn't quite sure why Emrys hates him so much.
Even from the very beginning, back in the tunnels under Camelot, Emrys has seemed to distrust him. He cannot think why. Ever since he was a small child he has wanted to meet Emrys, the greatest and most powerful warlock of all; and he cannot fathom why someone of such power would want to hid behind a facade of manservant Merlin.
But this is Emrys and he's not going to ask.
The next time they meet Emrys tries to get him killed at the hands Camelot's knights.
And again, years later.
But its aright. By that time Mordred knew he would never trust Emrys again.