Quiet is a mysterious woman with a variety of strange superhuman abilities. She's super strong, fast, and agile, she breathes and drinks through her skin, and she can become invisible, just to name a few. Her keen senses and skills make her a deadly sniper, and if Big Boss spares her life after their first encounter, she will join his side and become a partner on his missions. As her name implies, Quiet is unable to speak, and much of her character arc involves coming to understand her motivations and feelings. If you raise the bond between Big Boss and Quiet through the game, she becomes much more friendly with him, best shown when they share a happy moment together in the rain. If the player allows Big Boss to get really dirty and smelly during his time on missions, she will also force him to take a shower with her when he returns to base.
A great deal of Quiet's story is very spoiler-heavy, so please keep that in mind and leave spoilers out of the comments. Thanks!
Hope you like! I've got more posts lined up. Just gotta get the time to cap 'em with my new job and all. :P