I also love that, as the Doctor tries helps Amy and Rory’s relationship, he is wearing Dr. Frankenstein goggles while he tinkers with the TARDIS, tries to impress Rory with the TARDIS’ properties (and is miffed when Rory doesn’t make the “it’s bigger on the inside” comment), and then brings them to Venice for a date. I’m definitely seeing a resemblance to the Mickey-Rose relationship. He’s really kind of jealous of the Doctor and Amy (understandably…) and is pretty sulky—he’s a bit like Mickey, not too whiny though, but he gets on with the Doctor a little bit better.
When in Venice in 1580, the Doctor and crew encounter an apparent cult of vampires—which we were not expecting at all. Amy decides to become bait so that they can sneak into the vampire’s mansion, but it looks like she’ll be bitten and really may not be able to escape that. There’s a master plan besides just sucking blood, and they may not be aliens. Rory and the Doctor go to rescue Amy and begin talking about the night Amy kissed the Doctor, and the Doctor would rather go see the vampires.
The vampires happen to be from Saturnyne—they’re fish from space—who are wearing perception filters and have fled the cracks in space and time (often filled with silence) and are planning to flood and sink Venice so that they can repopulate their gene pool in an underwater city. They work well hiding as vampires because, as space-fish, they need to moisturize (remembrances of Cassandra…) and they do this by drinking blood, but they will then refill the “drunk-dry” girls with their own blood, changing them into space-fish-vampire-girls as well! They will then repopulate the species with the other space-fish-boys swimming around in the Venetian canals. Again, the Doctor must make a choice between letting a species die or saving a human city—it’s his burden that he must constantly deal with.
The Doctor must be harsh with Amy so that she’ll leave, but also, it’ll establish enough distance between them, which is necessary if she’s going to keep her relationship with Rory intact. It kind of does nudge her out of her fantasy world and back into the reality that Rory is there and she’s engaged to him, not the Doctor. This episode deals with a lot of awkward moments between the trio, but it never went to a really bad place. They handle potentially overly dramatic and detrimental situations amongst the room with lightness and aplomb. Eventually, they gel as a group, and leave together, the Doctor and Rory following after Amy into the TARDIS as “her boys.”
At the very end, as they follow Amy into the TARDIS for tea, the world around them goes silent. The crack followed the space-fish and silence has begun to fall around them.
“They’re not vampires, they’re aliens! Classic.”
“Tell me your whole plan…someday that’ll work!”
“Pale, creepy girls who can’t be seen in mirrors and don’t like sunlight”
“I’m a Time Lord, you’re a big fish. Think of the children…”