Saw the movie 17 again last night and it got me thinking while it wasn't a great movie it could be a really good erotic story.
For anyone interested the movie is about 37 year old husband who gets transformed back into his 17 year old self but still in the modern day / normal timeline, aka no doover, same body just younger, wife and kids are still the same age, etc.
If something like this already exists please forgive me.
https://storiesonline.net/s/50906/a-stitch-in-time
Marsh Alien's 'A Stitch In Time' is a do-forward story.
Kid tell Santa he wishes he could avoid high school and go forward in time.
He gets his wish. A 14 year old nerd wakes up in a 17 year old jock's body. His mom is dead, his dad remarried to a bimbo and another version of him has lived those years and become every thing he detested.
How can he recover his friends and family and make right the damage done, while hiding the fact that he isn't the kid they think he is and doesn't have the knowledge or maturity from those missing years.
Not exactly what you requested but a well plotted, different story with high sugar content at the end.