The Passage was fairly top-heavy with lake monsters, even if you didn’t count the various ghost ships that haunted Lake Oolingay. Really, most rural lakeside New England towns don’t even have one, and Martin’s Passage had two. One, of course, was Mortimer Marshall, paterfamilias of the extended Marshall clan who grew larger and more fish-like the older he got. The other was his grandson Harry, who thanks to a bargain his parents made with a witch, had taken a slightly different course in his water-related monstrosity, and now wore gloves and long sleeves even in the summer to avoid physical contact with anyone and didn’t sing in public if he could help it.
That was more than enough lake monster for anyone, but a tourist had seen an incredibly impressive horse for sale when the Market came to town earlier in the summer and had just had to buy it for what had seemed the quite reasonable price of a jar full of sweat bees.
Of course, once he’d bought the horse and gotten it delivered to his summer house on the lake, as soon as it caught sight of the water it had dragged the man beneath the waves and eaten all of him but his liver. Now it was roaming the shore at night, trying to lure people into touching it so it could stick to them like glue and drag them under to be devoured.
Mortimer Marshall did not approve of having random human livers floating in what he regarded as his lake, so the water horse had to go.
And so it was that various members of the extended Marshall family were employed to stalk the lake shore, waiting for it to make an appearance. Tom and Richard, the oldest of the youngest generation took point in the Lakeshore drive dive bars, in case the horse had worked out the knack of turning human, as Tom’s research indicated it was possible. The Boyds, even the dead one, kept an eye on the rental houses on the other shore. Harry’s parents watched the bridge, leaving Harry to cover the section of shore where the Devil’s Ravine fed into the lake.
They almost got it the first night- Johnny Boyd had tried to ride it, but it couldn’t eat or drown a ghost, and that distracted it long enough for Ernest Boyd to shoot it. Alas, Erne hadn’t come loaded for asshole fairy horse, on the grounds that most of the same sort of bullets that could hurt an asshole fairy horse could also hurt a phantom motorcyclist cursed to race whoever challenged him.
It was more cautious after that, and avoided that section of the shore entirely. It didn’t seem to have picked up the knack that Tom was worried about, so it never went to Lakeshore Drive (Which may well have had as much to do with the presence of the Lakeshore witch as anything the older brothers did or didn’t manage. Magical monsters tend to learn fairly quickly not to trifle who goes by a magic title instead of an actual name.)
Eventually, of course, it had to feed, and came ashore again, and did so at the inlet where Harry was waiting. And thus there came an impasse. Both were water monsters that fascinated people into drowning, and the horse was much more practiced at it; it lowered itself, trying to attract him onto its back. Harry…sang to the horse, voice cracking a bit, which, unfortunately, encouraged to horse to do dangerously suicidal things to try to impress him, which is what it was trying to do in the first place. Neither could really overcome the other, and they certainly couldn’t drown each other.
…Which is why it took another monster to settle things. The horse was not, to be honest, expecting a giant fish man to loom up out of the water behind it, and grab it in both webbed and clawed hands to twist it apart. But very few people expect that sort of thing, even when they aren’t anthropophagic water horses.
In the end, the horse’s own liver was left to float on the lake’s surface, as part of some sort of poetic justice or incidental irony.
Harry, for his part, resolved to take singing lessons, as soon as he could find a tutor who could hear him sing without trying to get themselves killed. Just in case.