anatsuno linked to a Merlin tentacle porn manifesto, and it's fantastic, full of clever thoughts and links to good fic (mostly BBC Merlin/Arthur).
RPS makes it harder to incorporate tentacles, but AUs are good :-) I only remember one for Lotrips:
- "Pet" by anatsuno & shaenie, (Elijah/Viggo)
[alternate site, shaenie's part 3]
- LOTR RPS: Elijah as a defiantly independent (but broke) scientist with a tentacle fetish. Viggo as a man who has found, or been found by, an alien with a sensuous nature, which he thinks of as Pet. Viggo who has a direct brain connection to the Pet, and to his spy cameras in Elijah's apartment. When they finally make contact, Pet and Elijah take to each other in very porny ways, with Viggo watching/feeling too. And the tentacle part is really sexy. Apparently destined to be a WIP forever, it's amazing as is -- a wild AU grounded in recognizable characters -- and it's really great and hot.
( Five more in other fandoms: )