What's the Name of That Book??? discussion

This was a Young Adult book I read around the early/mid 90's. A handsome stranger appears in the protagonist's town. Apparently, this stranger is some sort of sea creature disguised as a human, who is trying to seduce the protagonist's sister and possibly lure her away to the ocean, i think. Meanwhile preparations are being made for a sort of a festival that honors a local hero/legend that protects the town. A random citizen gets picked to represent the hero during the festival and is disguised with a mask. At the time of the festival, the stranger is discovered and tries to force his intended prey towards the ocean. The citizen disguised as the hero finds out and rushes towards the sea to stop the stranger, where an epic battle between hero and sea creature ensues. One important fact i remember clearly is that during their struggle, as the stranger gets closer to the sea, he gets stronger.

Try putting some of the story's keyword in the subject line--you'll get more hits that way.

Is the protagonist male or female? Is the random-citizen-dressed-up-as-legendary-hero part of the story outside of the festival and epic battle (i.e., a developed character)?

Sounds interesting.

I believe the protagonist is a female. The random citizen is a developed character, but no one finds out who it is until after the fight. I don't want to spoil anymore than that!

I'm starting to think that I dreamt this up... T_T

This sounds vaguely familiar, but I think that’s because there are some similarities to a part in The Scorpio Races. (But that wasn’t published till 2011 and the central plot is different.) I mention it just in case you’re combining parts of two books in your head or something like that.

Possibly Long Night Dance

A Stranger Came Ashore, by Mollie Hunter?

"When Finn Learson literally stumbles out of a stormy sea into a small village on the Shetland Isles, he steals the villagers' hearts. He's handsome and charming, he helps with the fishing and the harvest, and he's particularly drawn to Robbie's older sister Elspeth, with her beautiful long golden hair. Yet there's something about Finn that makes Robbie and his dog Tam feel uneasy. Haunted by local tales of the Selkie folk, Robbie suspects there's more to Finn than meets the eye. But who would believe Robbie's wild suspicions? As the story reaches its explosive finale at the fire festival of Up Helly Aa, can Robbie reveal the truth in time to save his sister?"

Robert wrote: "A Stranger Came Ashore, by Mollie Hunter?

"When Finn Learson literally stumbles out of a stormy sea into a small village on the Shetland Isles, he steals the villagers'..."

This is it!!!! Thank you so much! This has been plaguing me for years!