Hello, I'm having trouble with a story I'm writing. One of the characters is a new species/race that I created, they're immortal but age normally until the age of 18. He is the main love interest for the human protagonist and I can't decide to make him 18 years old or 18+ immortal years. I know there are some books where the love interest is immortal and centuries old (Such as Daniel/Fallen, Nightworld/L. J. Smith, Hush Hush/Becca Fitzpatrick, ect) but I can't decide if I want to do that or how to do it in a way that it's not... well creepy. So any opinions or advice would be very welcome. Thank you for your time.Answer:
I see the dilemma. On the one hand, if someone has centuries of accumulated wisdom and experience, it might be pretty boring dating someone who doesn't. What would they have in common to talk about? All the issues that excite and concern the young one would be stale bread to the other--and if that just leaves physical attraction to draw them together, that's when it gets creepy.
On the other hand, if you can find something of value that each can offer the other, you may have the basis of a relationship. The trick is finding it.
One thing May/December relationships sometimes have going for them (in fiction at least) is that the characters each find the relationship flattering. It can be a sign of status for a young girl to gain the admiration of an older powerful male or for an old man to gain the attention of a young, attractive girl. (Such a relationship is not always sexual.) Of course, in this case your immortal, because of his looks, may not have trouble attracting young women.
Still, that's not the best basis either. For a real relationship, you probably want them to offer each other something more substantial.
On the third hand, if you don't have a solid reason for making the immortal character old, if it doesn't add anything to the relationship, why do it? You may as well make them close in age so they have some common interests and concerns.
In other words, what do you want them to see in each other?
That's not really an answer, but I can't write your story for you. You have to figure out what will make your characters' relationship work.