Love — and, more to the point — sex, were baked in the vampire genre by Lord Byron long before Twilight reared its be-fanged head. But The Strain, which began as a mash/send up of horror and medical shows, had always avoided the gentler strains of romance. No longer.

In the latest episode, “Fallen Light,” of Guillermo del Toro’s meditation on blood (its haves and have nots) a rendition of “Misty Blue” plays over a flashback to Eph and Martinez hooking up at the dawn of Eph’s divorce before jump cutting to them in the present, broken, Eph confessing love and Martinez unable to respond. And they’re not the only ones with love lives in shambles: Dutch is left alone after choosing Nikki, only for her to skip town with her domineering mother. For Palmer, resurrecting Coco isn’t as permanent as he thought and must play nice with an increasingly antagonistic Eichorst if he wants to keep his boo’s heart beating.

Love is an unlikely theme given the shows premise, but it’s good for moving a plot forward. In some way or another, every character is driven or has been driven by love, romantic or otherwise. They do dumb stuff and, viola, plot.

As Setrakian said in the pilot, “Love is our grace. Love is our downfall.”

Speaking of the first season, the flashbacks here bring us to Eph and Martinez’s first encounter and attraction, and along for the ride is ol’ Jim Kent who is now dead. Sean Astin’s unexpected guest starring was a pleasant surprise, and it serves as a stark reminder of just how far the show has come along. As the minutes ticked away, I worried that it would abruptly end right there with Martinez shedding tears on her pillow.

But then, we’re in Quinlan’s oddly opulent base reunited with Gus, who has just equipped a solid twenty former inmates with an army’s worth of weaponry. Next week, Setrakian will be competing for ownership of the Occido Lumen at an auction against Eichorst. While Setrakian has sought help — and presumes he has it — from Quinlan and the Ancients, the closing line, which is an order to Gus, has made next week’s The Strain a necessary appointment. He’s going to try to kill Abraham Setrakian. Let’s see how that goes.