"Whatcha doin'?"

You ask from behind Bruce, accidentally and effectively scaring the shit out of him.

He turns a little green, but manages to calm down.

You're the newest Avenger, and you've taken that to mean you can come in and out of the tower whenever you please.

And you please often.

Unfortunately, that's where Bruce likes to conduct his experiments.

It's quiet here. Peaceful.

Until you burst in, that is.

You're so sneaky about it, too.

The last time, the first time you came into the lab and scared him, Tony was around. The two of you had an argument about it, and you left in a huff.

Tony is not here today.

Bruce turns and glares at you, crossing his arms over his still-rapidly-beating heart.

"...Studying."

He mutters, trying—and failing—to be nonchalant about it.

"How the hell did you even get in here?"