As much as we all dislike the Merlin, I don't see the Merlin being a black hat. If he wanted to, he could have let the Council die time and time again.
LTW likewise isn't corrupted, I would suspect, though his linkage is mostly to the fact he could have let Harry die several times, both in books and now in comic. And the Gatekeeper, the same.
Not saying the Council isn't infiltrated but I think those four (McCoy, Langtry, GK and LTW) can all be excluded.
This would leave Martha Liberty (who seems to garner the trust of LTW and Eb), Ancient Mai, and Cristos, if it is indeed infiltrated...