From Rivarly to Rings (PalletShipping).

Ash Ketchum, now sixteen and still blissfully oblivious to anything outside of training, battling, and winning, thought the most complicated thing in his life was choosing his next destination. Gary Oak, seventeen and trying to balance his prestigious Pokémon research with his career as the gym leader of Viridian City, believed he had everything under control and running exactly to his own high expectations. They were childhood rivals - always competing, always bickering, and always closer than either would admit - but soon finding a shaky truce and finally becoming good friends. That truce shatters when their casual Tuesday brunch at Pallet Town is interrupted as Professor Oak and Delia Ketchum both announce a pre-arranged, long-forgotten, and truly mind-boggling centuries-old family pact: Ash and Gary are to be married.

Forced to set aside their differences and try to make a future together, Ash worries about keeping the news secret from his friends, whose reactions he suspects would range from utter disbelief to outright outrage. He was dreading the inevitable chaos their engagement would cause among his extended traveling family. Meanwhile, Gary has a much darker problem: he was forced to break up with his girlfriend. Leaf Midori, a brilliant young woman battling her own demons, views the naive Ash as a threat to Gary's prestigious future. She doesn't handle rejection well - especially when the reason is someone she deems so utterly unworthy. As the two rivals stumble through their strange new reality, a storm of resentment, secrecy, and obsession brews, threatening to unravel more than just their engagement.

Rings were exchanged, but now a high-stakes rivalry for survival has truly begun...

(⚠️This fanfiction is rated mature; veiwer discretion are adviced⚠️)