I love having my Ebony wife dominated by another woman. They are usually BBW but feminine. They typically chain her to the bed and use instruments like feathers or vibrating toothbrushes to tickle and stimulate her sensitive parts. Some say it is hard to find a sub ebony woman, well, mine is definitely as sub as you can get in the bedroom!
The only thing I want to add to the past scenarios, very soon (and am actively working on it), is another cock in the room to participate in the fun and have it end with him fucking her.