First, if someone suggests this game handles coop poorly, remember next to nobody even attempts coop in iso crpgs. To me whatever flaws it has and it has some, it is still the best coop iso crpg experience you can have.
Personally I would have you and your buddy flip a coin to see who becomes the leader. Now sure you don't have to do this, but to me when you start bringing multiple heroes into the party and wanting to do quest lines together, it gets messy. You notice sometimes you talking has a different result in them talking... sounds great right? Well then you become a slave to both always trying to talk to see if there is something there for each of you or not. You find out it can be different, but most the times it is a waste of time and doesn't feel smooth and more a burden to try.
I'd do it where whoever wins the flip, picks the hero to play, the other 3 are characters you build from scratch and they listen in on leaders dialog vs mixing who's in control. I would ask the leader to always say out the line choice they are doing, so the other knows what they picked. This also adds a nice little role playing element without trying hard. For some reason, otherwise you have to scroll up each time to see what they picked as it isn't visible. (To me this is a pretty big coop issue.)
Also at the start of dialog the leader should tell the other (assuming you are on mic together) this is happening. The system only shows an icon on their avatar, it needs a Sound Option for this as well. Point is you want to know when the leader is talking to a NPC so you can listen in. Listening in is done overall well in this game.
After you play the game through crisply with one hero, now it is time to change sides on who leads, pick a new hero and teammates and do it all again and again.
I'm sure you won't do this, not that I mean that in a bad way, you'll try to maximize an all encompassing run, but to me it gets muddied that way and around a 1/3 of the way through it sinks in.... this could have been smoother if we had a true leader.Could be wrong.
