17 parts Complete I know I ship two of the triplets (Dewey and Louie) from Ducktales with Webby Vanderquack but I feel like Louie is the one most fitting for the roll.
There were once three prince brothers. Prince Hubert, Prince Dewford, and Prince Llewellyn, most commonly know as Prince's Huey, Dewey, and Louie. The trio seem like normal princes and brothers but there was a problem with Louie. Yes he was known as the evil triplet but there was something more to that. When he was just a baby he was sick with a plague but lived, only leaving him with the side effect of making him a monster every single night.
Webbigail or just Webby is best friends with the three prince's and always wanted to solve a mystery and go on adventures but she became suspicious of Louie, due to him being gone most of the time in the night.
Unknown to Louie, Webby always had a thing for him. Like playing and she makes him it on purpose or when he teases her . Even if he is a monster. Can this happen of will the entire country know what has become of their prince?