But no set-up about what actually happened to him (and why he is chasing them). In the novels, wasn't he chasing Mat to get the dagger? I can't remember.
In the novels he was still under the compulsion of the Dark One to hunt the three ta'veren. Or up to a point, as the compulsion was conflicting with his new Mordeth possession. Taking up the dagger in the Fal Dara dungeons resolved that conflict in favor of Mordeth, but to the degree that the Dark One's compulsion remained, it had metastasized into a hatred and desire to hurt the three ta'veren. In any case, he was clearly no longer compelled to follow them, since he moved away from them once freed of his cell.
“Tolerance is the virtue of the man without convictions.” GK Chesteron
Inde muagdhe Aes Sedai misain ye!
Deus Vult!
*MySmiley*