Yes, fighting beside people he barely knows, who he'd already have trouble identifying as friendlies, while his instincts try to tell him to kill everyone - that sounds about in line with how Roland's plans usually go. XD That sounds fun, let's do it!

I'm thinking after he sees some of those scenes of his past trauma he'd try to ignore how much it effected him and in doing so fall deeper into the mindset that makes it harder for him to fight the whole thing, so if we used Roland's history as the setting that could be a thing. If we did that their enemies would be the generic NPCs, as his traumas don't focus as much on actual enemies. Or he could walk into one of her memories, or each of theirs could sort of mesh together into one fun dual-purpose nightmare. Is there anything in her past you'd want to play with when they fight together?