Mo's since been given the rundown on what his being here means - primarily that it's a temporary thing - and while Alex now knows that Mo survived and all turns out okay, he's under no illusions of what his inevitable disappearance might mean. Alex clearly missed him, and Mo's sure that only having him here for a few weeks will seem a little cruel in the aftermath.

There are also advantages to being in a place where one apparently doesn't remember it upon returning home.

"How did you prepare your team for missions when you knew you were going to lose people?" Mo asks out of the blue one evening, when they're in private.