Shuri and Peter are geniuses.

And being a genius meant everything was boring to them.

So...

They made a toy...

A toy that...

Can manipulate human brains.

Well maybe.

They hadn't exactly tried it on a human yet...

And they weren't willing risk each other in fear of it breaking and not having the other's expertise to help fix it.

So they tried it on the Avengers.

The Avengers turned into babies.

Into FUCKING ADORABLE BABIES!!!

But being the geniuses they are, it would only last two hours as a fail safe. Or not.

You see, the fail safe broke and they were permantly babies.

Without the Avengers, the world collapsed while Shuri and Peter rose to the top as their leaders.