Multiples between me and partner or nope in general to a RP.
I mean, how else you going to tell a story with just two people? Multiple roles allows various cast to come in and fill in whatever gaps, be they mains (which I play two at most), side characters (also known as 'supporting cast,') or general NPCs (fillers for everything else.) Since I am keen on world building dynamics, multiple characters are a must for me. I get bored otherwise and lose interest if it is a story where me and partner are just playing one character and nothing more. I also quickly lose interest if partner wants to play just one character and expects me to play an entire gang.
I believe a good number of people are normally turned off by the multiple, role concept since they most likely feel, with multiple roles, you have to play them all out in same scene. Even I do not do that, as that gets hectic. I use them in a 'revolving,' cast way to keep the story going; usually by alternating between mains point of view and/or supporting roles when it calls for them. That way you still have singular pairings going on(less you involve supporting cast/NPCs in mix) while you and your partner's other characters still wait to be used elsewhere when you find a good pausing point for said scene, before moving on to the next.