I mean, how does one have the ability to trance? The description in the game is quite vague, I think Steiner said "Only chosen ones can achieve it" or something, but is there a more detailed explanation in the game that I might have missed first time round?

I only ask because I'm playing the game again now and Marcus is in my team and I'm on the world map levelling up, and he can't get trance, which is a shame. I guess it's only for the permanent playable characters, but still.. is there a more logical reason for it?