I’m new to bass, but I’ve been developing my theory on the Role of Bass based heavily on my longtime experience as a social dancer.
In social dance, you typically have two partners the Lead and the Follow. The dance is a conversation between them and the music. The Lead gives the impulses that move the partnership around and typically initiates all core body movements (the traditionally male role if you are imagining Fred Astaire), and the follow… follows those major movements adding characterful interpretation and embellishment to them (the traditionally female role if imagining Ginger Rogers). I often describe the roles as “The lead decides where you’re going. The follow decides how you get there.”
Playing music in an ensemble is also sort of a dance. I see the role of the lead and of the bass to be very similar. You are linking the rhythm, the pulse, with the melodic or lyrical.
In dance, the lead typically moves a lot less than the follow. They might stay in a space 1 yard/meter square, while the follow moves and spins all about them. You have a lot of room to add embellishments, but if they get too busy, they can easily confuse the major impulses that you are trying to communicate. If you know how to do it right, you can still isolate your embellished movements from the major impulses you’re trying to communicate.
As an example - I often have wild syncopated and slidey feet, but they don’t move my core until I want them to, and then that movement is very definite. Now think of Geddy Lee playing “Tom Sawyer”, he is dancing all over the line but he hits a solid root right on the 1 of every line in the breakdown. Same thing.
And also, if my partner has been spinning around or moving all of the floor a lot. It’s best for me to give them a break and throw in a couple spins and slides of my own to keep things moving while they collect themselves.
If I’m dancing with a less experienced partner, I have to be more definitive and overt in how I communicate. If I’m dancing with a very experienced partner, we bounce ideas off of each other much more fluidly to the point where the distinction of “Lead and Follow” blurs.
As has been repeated - It’s all about serving the song. But having a traditional role in a partnership and understanding how it works, what the rules are, when to bend them, and when to break them are part of serving the song/dance.