Katsuki was married to Izuku, Katsuki was the dragon clan king and Izuku was the saltwater clan king and also a siren. Izuku had the power to turn others into merpeople, sirens, and tritons, which is how he and Katsuki merged their kingdoms during their marriage. But one day Izuku was caught by a net of pirates, Katsuki was with him and was attacking the ship trying to save him by dragging the net to prevent that. After the attack, they realized they could no longer trust humans. They would always help ships and guide them on their way or give them supplies, but now after they attacked the kingdoms royals and Katauki’s mate… They made a law of no merfolk was to help them any longer, if any of the sirens or tritons saw a ship they were to destroy it. And that’s how the Bermuda Triangle came to be feared by humans… Izuku and Katsuki were currently sitting on their throwns in the saltwater kingdoms castle.