Help. I have no idea what I wanna do. blargh

I HAVE AN IDEA. So this thought came to me by a title of a story. Hopefully I can make it myself though possibly no...too many variables that suddenly entered my head.

I'm planning to make a story about the Heartless of Kingdom Hearts. just 1 Heartless. Maybe. Hopefully. Sounded a lot more interesting in my head and it may also be a crossover since I don't really want to add much from Kingdom Hearts itself so yeah... the idea is as follows:

Sora and Riku were not the only ones to leave the Realm of Darkness through the Door to Light. A Heartless followed but while passing through was sent through a different world altogether due to the world collapsing. This is its story.

so possible Crossovers are:

1. Kingdom Hearts X RWBY: why? why not? also since Grimm and Heartless are kinda similar. so yay. Still having variables.

2. Kingdom Hearts X Highscholl DxD: why? again, why not? also since I thought that there can be quite the interesting premise made in it. Still having variables.

I'll make more when I do. These stories are some that I'm planning on making but for those that intend to do so go ahead I guess...also haven't decided on what Heartless either...though if you guys did get it from here at least link me the story? And credit me? Maybe not that last part but yeah...

I had a new idea but I already forgot it. Damn it.