As science geeks turned heroic S.H.I.E.L.D. agents, Fitz and Jemma (Iain De Caestecker, Elizabeth Henstridge) have fallen in love, sworn to be together forever, then barely been together at all since, as their respective fates have thrown them into alternate universes and timelines. At the climax of last week’s show, they finally were about to be reunited – but as prisoners of aliens aboard a hostile spaceship. This week, the long-separated duo finally gets to share the screen – but it’s in a series of flashbacks, captivity sequences and alternate reality scenarios that really puts the characters, and the actors, through their paces.