One thing writers latch onto is the almost procedural nature of their partnership—it's all about peeling back those professional layers. The initial dynamic is pure mutual respect between a soldier and a marksman, all clipped radio chatter and battlefield efficiency. Fics often exploit that by putting them in scenarios where the mask slips: Garrus making a dry comment after a close call that catches Shepard off-guard, or Shepard noticing the specific way he calibrates the Normandy's guns when he thinks no one's watching. The tension builds from those tiny, shared moments of vulnerability that their formal roles don't allow for.
A classic move is using the Citadel meet-up as a turning point. In a lot of stories, that's where the shop-talk finally gives way to something personal. Maybe Shepard finds him on that balcony, and instead of just debriefing, they end up talking about Palaven, about loss, about what comes after. The dialogue shifts from mission parameters to unspoken things, and the fic lets that quiet hang in the air between sentences. You can feel the pivot from commander and crewmate to just two people, and that's where the possibility ignites.
From there, it's often a slow dismantling of boundaries through shared trauma and dark humor. They've seen the worst together, so the trust is absolute, but translating that into romance means navigating a minefield of protocol and personal history. The best fics make you wait for it, letting a brush of hands during weapon maintenance or a shared, grim joke after a mission carry all the weight. The payoff isn't a grand confession; it's Shepard finally dropping the 'C-Sec' or 'Vakarian' and just saying 'Garrus,' and him responding in kind.