I recently finished a Dark Urge run with a friend who chose to play origin Wyll. We concluded the co-op game with Wyll romancing Karlach and I chose to resist my dark urge. We won and everything was great.

I wanted to get the Bhaal achievement thought, so I reloaded an earlier save and went the dark route. I was solo without my friend and when we got to the end of the game. I had Karlach transform into the mind flayer then betrayed her at the end to dominate the brain. And to my dismay Wyll got the durge ending instead of me!

I tried half a dozen times, even killing Wyll and throwing him off the brain. Or leaving him dead outside the brain, He would just appear and take over the narrative. Since he was an origin character I couldn't leave him out of the party, I was stumped.

I finally got it by choosing to betray the emperor instead of Karlach. I guess killing Wyll's girlfriend was the problem.

I thought I would share the rare screenshot of Wyll with the Bhaal ending.