No Mutants Allowed

They presumably died due to their inability to follow me onto a ship without my explicit instructions.

I made that mistake the first time I played. I left Marcus there, and then there's no ending slide for him....

Wah? Is there a way to fix that? I left them there but haven't left the rig yet. In fact I'm talking to Richardson right now.

@R.Graves Head back to the entrance and relocate your companions to the room where Horrigan confronts you, then pick them back up at the end of the game. You should be able to save them so long as the generator hasn't been destroyed.