My friend and I are band mates in a Country band. Been playing together for about 8 years. He plays electric bass and I play rhythm guitar. We have started playing together at a nursing home each Monday afternoon.
He is now on rhythm guitar and providing the vocal lead. I'm on a brand new electric bass with three weeks experience. We've played two gigs so far, not great, but - no one got out of their wheel chairs and ran out.

They all know us from the other band - we have been playing for them once a month for years.
Mostly new songs I've not played before, still all Country, just a new batch. He only has the lyrics on the sheet music he plays from, does not play from fake chord,
so he is winging a chord progression. I'm doing the same - winging a chord progression and playing a Root or R-5 to what I hope he is doing. I understand about watching his hands, and we have played together long enough that I know he is not going to venture very far from a I IV V chord progression. It's pretty much a jamm session, only problem is I'm new to bass.
That's the situation, HELP, looking for any hints you guys/gals can provide.
Thanks,
Malcolm
P.S. Might help if someone would tell me what exactly a bass line is. I know what Wikipedia says, but would appreciate your thoughts.