Please remember, whether your partner would or wouldn't ask this question or you would or wouldn't be interested, try to answer it as if they did ask and what your first choice would be. Yes, it's fantasy!
If your partner asked you to participate in a threesome to make their fantasy come true, and they told you that you got to choose who was involved and whether or not your partner participated or just watched...what would the sexual makeup of your threesome look like?
Disclaimer: I use male and female as which ever sexual orientation you identify with. My apologies if I missed a needed category!