The First Nate/Bianca story to my knowledge.
(In this story Nate is 16 and Bianca is 18)
A terrorist plot by Team Plasma left all of Nate's Pokémon dead, thankfully he wasn't harmed but since he collected 8 Badges with all of his Pokémon gone he fell into a depression.
Nate walled down the street of Aspertia City with tears slowly going down his face, in mere seconds his all of his Trusted Pokémon were gone.
He walked up the Lookout point and sat on the bench, suddenly a figure walked up to him, It was Bianca. "I've heard the news." Nate said nothing.
"I loved all of those Pokémon, and now they're dead.. all of them." Nate's mind flashed back to that explosion. All the screeches His eyes got filed with tears.
"How can I become Champion now?" Bianca smiled "Look Nate, As soon as I heard the news I wanted you to have these. "she took out a Marrowak, Sylveon and Inceneroar.
"Are those for m-me?" "yes, Sylveon is a Fairy Type meaning the they'll be immune to the Champions Dragon moves, Inceneroar has a Dragon Z-Crystal which means that he'll be able to do a powerful move once per battle, and since he knows a Dragon Type move he'll do tons of damage with the Dragon-Z stone without being damaged by the Dragon's attacks."
Bianca smiled "What about the Marrowak?" Bianca looked embarrassed "O-Oh sorry I brought her out by a mistake."
Nate smiled "It's ok, oh and Bianca.. Thank you." He gave her a kiss on the cheek. Bianca returned the kiss by kissing him softly on the Lips. Nate used his Pokéballs on the three Pokémon as he walked down the steps "Wish me luck." Nate said to Bianca as he walked to the legue."
"Love you."