yeah I think you're best bet is to talk to the dude and both of you can alternate between lead and rythm, if you have to have it so for half of the song he is playing lead with you as rythm but for the other half of the song you could be playing lead and he could be rythm... besides if you play lead for every song and he plays rythm for every song then there won't be much variety in your music and you'll both probably get bored before long.