How to train your __________.

So basically had this idea on my head for a while. It’s a rather simple concept But if there is a plot it could be super deep and such or just keep it as simple as the idea is. As for the blank part it could be anything, a character you have made up a while ago, canon character from a series, or even something like a monster for example a succubus. It would all depend on what we are feeling like. It’s a rather simple explanation but we could talk about it in ecchitexts if you find yourself interested.