ok explaining the piece here bc there's like four things going on. so they're pointing at each other's backs, because roy burning riza's back and also riza being the one to shoot roy should she falter. backs (and fronts) bare to each other bc of their absolute blanket trust of the other, but military slacks still on bc their relationship cannot get farther than what it is. to bring in the prompt, both a crossbow bolt and a bolt of lightning, originating from the opposite of who you'd expect, bc their direct responsibility in creating the other (riza showing roy the secret of flame alchemy, roy inspiring riza to follow her to the military). <- although, it is not exactly what their ability is, just very close to it, hence the origin from the opposite person (but im sure riza could rock on a crossbow). and i uh. think that's it