Writer: Eric Charmelo, Nicole Snyder
Director: Phil Sgriccia
Sam and Dean investigate a set of murders on Valentines Day and discover they are dealing with an ancient curse. Once kissed by the curse, the person is marked to die.
For this episode: 3 humans (one of which was a witch) and 1 qarin.
For the series so far = At least 1214 humans (of which 15 were witches), 1124 angels, 182 demons, 71 vampires, 52 ghosts, 36 Jefferson Starships, 22 gods, 19 zombies, 12 werewolves, 10 hellhounds, 7 shapeshifters, 7 skinwalkers, 6 changelings, 5 djinn, 5 reapers, 4 dogs, 4 ghouls, 4 Leviathan, 3 Khan Worms, 2 Amazons, 2 arachnes, 2 kitsunes, 2 rugarus, 2 Thule, 2 vetalas, 2 zannas, 1 banshee, 1 cat, 1 crocotta, Death, 1 deer, 1 dragon, 1 fairy, 1 familiar, 1 lamia, the Mother of All, 1 nachzehrer, 1 okami, 1 phoenix, 1 pishtaco, 1 Purgatory creature, 1 qarin, 1 rakshasa, 1 rawhead, 1 shojo, 1 shtriga, 1 siren, 1 Titan, 1 wendigo, 1 whore of Babylon, 1 wicked witch, and 1 wraith.
- And Show It to You: The qarin kills by yanking out the heart of its victim.
- Book-Ends: The episode starts with Sam lying in bed unable to sleep, consumed by what Lucifer said to him in the cage, while Dean snoozes away. It ends with the reverse, Sam sleeping peacefully while Dean, wide awake, frets over what Qarin!Amara's appearance means for him.
- Continuity Nod: Dean's Valentine's Night trolling for easy pickups has been noted before.
- Covered in Kisses: Dean sports a hickey at the beginning of the episode, evidence of his previous night's activities.
- The Reveal: Sam knows about Dean's feelings for Amara.
- Running Gag: Over the course of the series, the brothers often choose who has to do an unpleasant task by playing Rock, Paper, Scissors. It is established that Dean always loses because he always plays scissors, despite the fact that Sam has repeatedly told Dean that he knows Dean will play Scissors. The boys play to decide who will return upstairs to look for the qarin's heart and who will search the creepier downstairs basement. They play and both are visibly surprised when they tie because Dean plays rock. They play a total of three rounds with Dean finally winning by playing paper to Sam's rock. Both brothers are so shocked that they are speechless. Sam, confused, heads upstairs. Dean, thrilled over his rare win, does a victory dance into a veiled part of the basement, forgetting that he'd won the right to search upstairs.
- Shout-Out: As a few have noticed, the qarin's shapeshifting and "venereal" way of passing from victim to victim are reminiscent of the monster in It Follows.
- Wicked Witch: In spite of her claims of being a white witch (a witch that practices benevolent magic), Sonja designs her spell to kill the caster of the spell and anyone they kiss.
- Your Cheating Heart: Melissa initially seeks out a "return to love" spell after her husband, Dan, begins an affair with their babysitter, Staci.