At the Mother Base, Miller was against keeping her, but Big Boss trusts her(temporary) Quiet is best at sniping with all her supernatural powers. She can almost turn invisible as she moves so fast. But Do you want some more from her? Here is how you can have a shower with her in MGS V: The Phantom Pain.
So Starting with your reputation in the game, you need to build your full trust with Quiet. To Gain her trust, you need to take her in your Main Missions as far as possible. Now after you have gained maximum trust, take her to a mission and simply wait inside the next dumpster for a week.
NO! I am not kidding, you have to wait there for a week. You can have your Phantom cigars with you if you need. As the time(one week) is over, you’ll see and hear some flies around you just after you leave the dumpster and return to your Mother Base via Chopper.
Now is the Fun part, as you will return Quite will ask you to join her for a Shower and the rest you’ll see in the video below. Enjoy:)