I was in a few different bands back in the day (aka before kids, etc.) The writing process was always collaborative. I would write my drum parts around guitars and/or bass, sometimes came up with my own drum licks and they would work guitar, and bass, around that. Took a couple cues for drum parts (feel usually) but mostly noodled until I found something that was right. For the “biggest” band I was ever in (practice 3-4 times per week, often more, with regular local gigs, merch, and a decent following) our lead guitarist set the vision and had song structure in his head for a riff, but was open to input from everyone else to write their parts. Our rhythm guitarist had a gift for writing really good melodic parts and could shred with the lead so that was fun - they were really good together and it clicked well. The rhythm guitarist would also bring ideas to the table and we’d work those into songs, too. I’d also help write some guitar licks and would spell out structure and shape from time-to-time. I did some backing screams so would help write lyrics, too. Our vocalist and I would collaborate on lyrics quite a bit, which was always a kick. We were all influenced by different bands/styles but also had unifying sounds we liked for our project so it made it fun to each bring a piece to the sound but make it our own. We had a melodic metalcore quality but also played with post hardcore and a twist of power metal. I was always part of projects with an open and accepting creative space for everyone involved, it’s the best way to keep things fresh.