I've been doing remote recording sessions for over a decade and you learn how to create interesting parts that fit a song. After a while you develop the skill of coming up with bass lines, fills and solos really quickly.
Check out the video for a full song breakdown and loads of tips on how to make up your own bass lines.
Here's the song in its full glory.
For loads more on how to create bass lines, fills, and solos, browse the lessons below.