Literary version:
The old castle on the high cliff is the coffin of the vampire
The abyss under the sea cliff is the graveyard of the Kraken.
Vampire × Siren
Real version:
As the unrecognized illegitimate son of a prince, Xia Yan chose to stay away from the hustle and bustle of the world and locked himself up in a high clifftop castle as if he had cut off his love.
Similarly, the little siren prince of the previous generation lost all his relatives and friends after surviving the Year of Catastrophe.
Motto: Love knows no race