Canon scents!! This one is perfect for me bc my main memories from this life are sensory based, and scent is a big one!
The main scents I associate with being a Flametrooper in the First Order are harsh chemical cleaners and smoke of any kind. (Well. Smoke from fires, specifically.) Oh, also any flammable fuel.
I wanna yammer about scents from that life a little, actually.
I remember the harsh chemical scents from when we were cleaning + maintaining our armor and the locker rooms. The smell of the fuel when I would get my fuel tanks refilled. The acrid smoke scent that would cling to me after a burn raid. I could be in the sonic for an hour, and I could still smell it.
The air in a destroyer was scrubbed and recycled. There was a very specific scent to it that varied ship to ship. Not by much, but enough you could pick up on it if you got transferred from one ship to another. You'd become noseblind to it pretty quickly, though.
~ Your friendly neighborhood Flametrooper