Hmm...

You know you can change chords if you want, right?

There's all sorts of music theory involving complementary chords, scales, tonics etc.

You could just bury yourself in all that for a bit and then try to write music.

Or you could just play with patterns in a sequencer and see what sounds good.

I'm sure either way yields good results if you're willing to put in the time & effort... though I know which one seems more fun to me!