Compare guitar 2 and bass in the song tab here- GnR - Nightrain.
If you look at the notes played by bass relative to the guitar in verses 1 and 2, you can see instances of Major 6th, Minor 7th, Major 2nd etc. Im wondering did the artist(bassist) arbitrarily thought to choose these notes or is it more of an example of a moving bassline- one that moves away from the root note to other intervals and returning back to the root?