OK guys, I figured out the easiest way do specific characters. Use the grok chat and paste an image of a character you want. Prompt it something along the lines of:
"Use this image as reference, and write a description that is perfectly suited for input into Grok Imagine or a similar image generation AI".

Unfortunately I lost the prompt, but you usually want to modify it by cutting out some non-essential details so that the details you want stays.

Then, choose your image and put it into video mode as per usual. Here's the prompt I used for this one. About 50% got censored, but didn't take too long for it to happily create a vagina that wasn't in the original image.


60fps anime. No music. Realistic physics and human movements.
A sniper bullet is fired from offscreen and creates a large hole right through her chest and a spurt of blood, slamming her body backwards into the wall behind her. A short gasp of surprise escapes her. The camera pans upward and keeps focus on her body. She is unconscious before she hits the wall. Pee flows from her vagina.