Levi gets flashbacks quite a bit, but he can suppress them easily enough. Until one day where the flash back is so real, so vivid that He starts quivering and shaking in his desk chair as he tries to keep his emotions in check to no avail.

"T-tch.. d-damn it.." He whimpers as he sees every painful memory of his fallen comrades. It hurts his soul.. He can barely think straight.. barely see what's real and what's fake.. you happen to be in the room when this one happens.