Swapping 3D models is usually one of the first mods folks figure out for games without official mod tools, letting you earnestly play as different characters or just dick about and make things weird. Well, folks have been fiddling with Metal Gear Solid V: The Phantom Pain [official site] and sure, you could make it so Quiet takes Snake's place.
Or you could swap D-Dog for Quiet, making some of the sniper's already-odd cutscenes get really weird. It's a simple thing and entirely predictable but, like physics ragdolls freakouts and missing faces, I will always laugh at model swaps gone wrong. Look, this dog thinks he's people (sorry, I don't have a better source for that):
The cutscene that clip's from (spoilers, obvs) isn't much less weird though (oh, Metal Gear!). While D-Dog's model is evidently set up similar enough to do something in this scene rather than nothing, it's different enough that it freaks out - unsurprisingly, seeing as he's not people. Other human characters, however, swap almost perfectly. Here's what happens when Quiet and Ocelot change places:
Replacing DD with Ocelot is even weirder:
It's all so goofy and I can't help but laugh.
I roll with Quiet usually, tranqing entire outposts unseen under cover of night as a crack team with careful coordination and timing. Many military games dabble in giving you sniper cover for a brief scripted sequence, and I always enjoy that, but this lasts for as long as I want. It's brilliant. And yet... I miss my dog buddy. I might see about using Diamond Dog's model for Quiet. She's off in the distance most the time anyway but I'd get to ride with my (spasming, incorrectly-animated) dog in the helicopter.