I have an idea for you, but I don't know if Vash would be a great person to be part of this.
So Rome is the Philosophy teacher, you could have a student be surly/discontent/etc about a concept they had to learn.
For example, if Alfred wanted to do this, you might take Plato's quote "Democracy passes into despotism." and he might argue that it wouldn't do that or something. lol I combed through Plato quotes quickly to find one, so that might not be the best example.
I don't picture Vash as a cunning debater (more like someone who gets frustrated when he has to elaborate and people don't see his point), so I don't know if that'd make him a better or worse candidate than someone more likely to be fancy with words :P
I'll keep thinking for something we might be able to do together :'D