Ooookay, I was trying to write a light-hearted little Rom-Com about these two, and it sort of... Didn't happen. Welp, enjoy anyway!
Turians are not a species that would be classified as 'playful,' or 'lighthearted.' Do what you must for the good of the clan; the needs of the many outweigh the needs of the few. They were creatures of duty, habit, and diligence. Their idea of fun was a highly competitive sparring match, sometimes not stopping until one of them was out cold. They were fierce, battle-ready killing machines who were taught from a young age that defeat was disgrace, that giving an apology was a sign of weakness.
Garrus was no exception to this, having been thrust into the military world at the standard age of fifteen. He hadn't exactly objected; he was a little excited to enlist- it was something of a rite of passage into adulthood on Palaven. He had entered base camp as a starry-eyed, awkward teenager, and returned to his family a battle- hardened adult.
Even when Garrus joined the Normandy crew, he kept to himself, preferring to repair and calibrate the Mako rather than socialize with the humans, who were more than happy to leave the tall, intimidating alien alone. That's how it always was with humans. Aside from a quick 'hello' from the bold ones, they averted their eyes and walked a little faster when they saw him. He could see where they were coming from. He was big, even for a turian, walking at least a head taller than most other species, and he usually had a rifle on his back. He supposed he wasn't overly inviting.
And then he met Shepard.
She'd smiled when he had talked to her on the Citadel, making conversation easily and not once did he see fear in her eyes. Instead, she offered her hand to him with no hesitation, her deep blue eyes studying him intently. When he didn't know how to respond, she laughed, picked up his hand with her own outstretched one, and shook it.
'I'll see you around, Vakarian,' she'd said before sauntering off to meet the Council, leaving him with his mandibles slack, his hand tingling from where she's gripped it, even through the glove. When she found him again and asked him to join her, he'd eagerly accepted. Within the day, he'd quit his job, packed up his meagre belongings and moved onto the Normandy.
Shepard came down to see him regularly, and they would talk about strategy and rifles for hours. Eventually, she began to share idle gossip about the crew- nothing serious, just what she'd overheard herself- and beyond all odds, Garrus made his first human friend. He taught her how to sight a target more effectively, she taught him how to fight hand-to-hand with someone more flexible than a turian. She showed him how to resolve conflict with words instead of violence, he showed her how to repair the Mako herself.
From him, she learned fierceness. From her, he learned kindness.
They're just so cute I can't handle it!