Folks:
Honestly, there is a lot of Garrus-Shephard erotica out there. However, very few of the stories deal at all with the mechanics of the relationship – they are all about the emotional aspect of it. Many of them are even well written. But I felt there had to be something on the sheer fact of the difference in the physical bodies, even if it was short.
Just a couple of pages on the way I imagine Garrus to be. You probably won't get the story if you haven't played Mass Effect.
-Elenia
Like all turians, Garrus' skin was hard and almost chitinous on most of his body - it had been made so by their species' evolution under the harsh suns of their planet. Still, there were softer places on him, places that felt almost like a smooth, thick leather, and Shephard particularly enjoyed seeking these places out with her fingers or even her tongue.
Behind his ears, for example, there was a band of this softer skin, and he was particularly sensitive here. The base of his neck and his chest were both substantially softer than his head. His belly, too, was flat and taut and covered with smooth skin, as were his...she supposed 'palms ' were the best word, even though he only had three long slim fingerlike appendages.
And of course, his cock. His cock left her sore and chafing and achy even with copious amounts of lube and she knew he worried about it but she didn't care. The delicious friction when he was inside of her was more than worth some soreness afterward.
His whole body was like that - frightening, alluring, and very powerful, and powerful and dangerous things attracted her. She would probably never cease to shiver a bit when his talons wandered near her sex, but he had learned to temper his touch to her soft and sensitive skin, and with care he even slid his fingers inside her wet slit now.