How to Collaborate and Co-Write

I am looking at a different style of horror which I'm contemplating a pen named for but I haven't yet made that decision. That's mostly for sort of marketing purposes in the sense of like it's a middle grade horror a lot less dark a bit more pacy whereas some of the stuff I like to write is a lot more wayfaring and rich prose and very very dark so I'm potentially contemplating those two different audiences just to make it a bit easier to sell those books. But as I say I've not really made the decision on that yet because part of the reason that I choose to write is because I want to share the stuff that I do and so putting myself behind