So you want to play with random people, but you also want those people by chance all:
Stay in the mission for at least 20 minutes, have no emergencies or sudden visits or calls happen, stick to you like Robin to Batman, play at exactly your pace, do all the objectives for you, not use any nuke abilities and/or generally just don't kill anything they don't absolutely have to.
Ithink what you're looking for is a slave, not a random person.