A/N: Someone reminded me this story was open-ended, so I came up with a little one-shot :D Enjoy!

SOMETIME AFTER CIVIL WAR AND BLACK PANTHER AND BEFORE INFINITY WARS

Bucky found T'Challa hovering outside the entrance to his sister's lab. "T'Challa?"

The king startled nervously. "Ah, yes, hello."

"What're you doin'?" Bucky peered through the semi-transparent panel. Rosie and Shuri were doing, well, something, with a holographic interface and cackling madly. Both young women had tears running down their faces as they hung off each other's shoulders. "Uh, what're they doin'?"

"Honestly I am afraid to go inside and ask," T'Challa said wryly. "I knew I shouldn't have introduced them."

Bucky cleared his throat. "Uh, doesn't your sister run all R&D departments since she got out of school, anyway?"

T'Challa gave him a despairing glance. "Exactly."

They stepped too close to the door sensor and it triggered, opening the doors. As soon as they noticed the two men standing there, the girls went quiet, choking on their laughter. "Brother," Shuri said cheerfully, wiping her eyes. "James!"

Rosie waved a hand in greeting, still trying to choke down her laughter.

The two men exchanged a glance and chose the better part of valour. They turned about-face and walked straight out again.

The two girls burst into laughter as they left.

"I don't even wanna know," Bucky muttered.

"Nope."