Basic Trope: A male character starts a romance with a mermaid and can't figure out how to go all the way.
- Straight: Bob the human meets Alice the mermaid - they fall in love but can't make love.
- Exaggerated:
- Bob will vow to never have sex due to his love for Alice.
- Alice has an octopus' arms instead of legs, and so literally lacks a genital opening.
- Downplayed: Alice does have a fishy lower body, however there is still an opening for Bob to "work with".
- Justified:
- Alice the mermaid lays eggs.
- Cetaceans (and presumably also mermaids) have internal genitalia inside a cloaca- the shared orifice used by the vagina, urethra, and anus- and the cloaca is difficult to find.
- Inverted:
- Alice the mermaid can not figure out how to make love to Bob the human.
- Alice is a "reverse mermaid" (fish above the waist, human below).
- Gender-Inverted: Alice is a human woman and Bob is a merman.
- Subverted:
- "She has a mouth."
- External fertilization, like fish. "She has a hand."
- Turn out that part of her scales, just below her waist, are concealing a cloaca.
- Her lower half resembles that of a dolphin or a whale—both mammals—and is therefore "compatible".
- Double Subverted:
- Alice instinctively bites down like a shark when he tries oral.
- Alice is a human woman and Bob is a merman- and his genitals are retracted inside a cloaca when not in use.
- Parodied: Bob is a "mersexual" but has no idea how to make love with mermaids. It amuses mermaids to not tell him.
- Zig Zagged: Bob and Alice the mermaid can't make love. Alice has herself turned into a human. Bob turns himself into a merman. Of course since she was a mermaid until recently, Alice knows just what to do.
- Averted:
- Alice is a human woman wearing a prosthetic tail over her legs.
- Mermaids in this setting are aquatic mammals and possess a dolphin-like cloaca instead of external genitalia.
- Bob and Alice don't want to have sex.
- Alice has two tails instead of one, with female genitalia in between.
- It's a case of Barbie Doll Anatomy. The audience can't see Alice's private parts, but they're there.
- Enforced: "We can't have love making on screen. Make Alice a mermaid."
- Lampshaded: Bob: "I have to do WHAT?"
- Invoked: Bob is trapped on a planet of incompatible mermaids as a form of Ironic Hell.
- Exploited: Alice keeps Bob distracted with figuring out how her biology works while the villain makes off with the money.
- Defied: Bob has no problem working out the biology of her kind.
- Discussed:Alice: I'm ready Bob, take me now!
Bob: How do I do that?
Alice: Loser. - Conversed: "Oh, god, how many more times will we have to see this plot point happening in series who include mermaids? Can't they just have a series where the mermaids either aren't involved in romance or have it with their own kind?"
- Deconstructed:
- Despite superficial similarities, mermaids and humans are far too biologically different for a romantic or sexual relationship to work. They have fundamental misconceptions about how such a relationship would work - Bob can't get past her lack of 'equipment', Alice doesn't understand why he sees sex as more than just reproduction. They have a short, rocky relationship and go their separate ways.
- Alice, as a mermaid, has a dolphin-like cloaca that is the shared orifice for her vagina and anus. Bob is averse to inserting his dick into the cloaca because he is neither into anal nor has a scat fetish.
- Reconstructed:
- Bob has a fetish for mermaids, and Alice has a fascination with humans. They make it work.
- Alice and Bob decide that the emotional relationship between them is more important than having compatible equipment and that being a Chastity Couple is enough for them. And it doesn't necessarily stop them from going to second base if they really want to.
- Played For Laughs: "I put it where?"
- Played For Drama: Alice thinks because of this problem she and Bob were never meant to be.
Back to the Mermaid Problem - we think the answer may involve seamen.