After a little messing around with Hydra I came up with an idea that kind of allows you to make a drum pattern/bassline/riff/etc “evolve” only by turning a knob. I hope I can explain in decently, here’s a pic:
The heart of the concept lies in the “scale” parameter of Hydra. The drum track has 3 parts: hats, kick, and snare. I set one knob to control the volume of all three of these. I set the scale on Hydra, though, so they would all move at different rates. The hats get loudest first, then the kick, then the snare. As I turn the knob, they fade into the mix at different rates. I then applied a gate to stop the kick coming in before the hats got decently loud, and same with the snare. Finally a send track with source muted.
edit: forgot to mention that the knob is set to hydra input, may have been obvious though
Next I applied to the same idea to a bassline, but instead of different drum hits on each track, I did more notes. When I have the knob turned 1/3 of the way, a simple bassline is playing. 2/3, and the bassline gets more complex, as more notes are added. 3/3, and even more notes come in.
double edit: Just realized I sent all the bass tracks to the drum send instead of bass send. Not sure how I missed that, it was pretty late when I did this though.
I just wanted to share that, personally I think it sounds pretty cool. If I was not clear just ask for clarification.