A little discussion about rivalry in romance stories (Patreon)

I was reading a few romance mangas here and there just to get some reference for future stories. Some of them are fine, but some of them made me question whether I should use these for future chapters.

As you read Chapter 3, I was teasing Serena in the final page as a "potential" rival or probably not. But I am going a different direction on how to handle her in the story and make her a bit unique in the upcoming chapter and making sure avoiding some of the common tropes of a love rival like you see in the genre.

However, there's is a matter of making a male rival that competes against Calem for Hex's affection. I did have a draft/sketches for this character, and he is an existing character in the game, but (spoiler alert) he an NPC character that you battle in XY. But I'm starting feeling a bit hesitant to use this character since  he's just an NPC in game and he doesn't exist in other media and doesn't have any significance in the story.

So using this NPC who has no history with the characters or any significance at all just for the sake of Calem's "Love" Rival makes me think twice on using it. But at the same time, I want to ask your opinion on the matter, whether you vote on the polls or make a discussion in the comments section. I would love to hear your thoughts about it.

edit: While the character in question doesn't have any backstory, I'm planning to add one in the specifically for him, and he is technically an Original character in terms of backstory. So they kind of a history together.