It was an accident

"I... it was an accident," Kate said. "They, er, got caught in a door, and by the time I could react they were gone. Car door, I mean."

"Your clothes got... caught in a car door?" Mary said.

"That's what I said."

"All of them?" Mary said. She blinked. "Even your underwear."

Kate blushed slightly. Mary quickly continued.

"Alright then! Okay, that sounds... unlucky," Mary said.

"I didn't exactly want to run through the street naked!" Kate said. "This place was closest, I just got here as fast as I could. Not like I'd plan to do something like that."

Kate shivered slightly, reddening all the more at the memory. Mary eyeing her wasn't helping matters.

She was aware the story was a rushed concoction, but they were in Gotham, stranger things happened every other week. And Mary could be... credulous. Judging by her newly sympathetic expression, Mary seemed to believe her.

"I'm sorry," Mary said. "That sounds awful."

Kate opened her mouth to speak, then bit her lip as Mary moved in for a hug. It might have been comforting other times, but Kate had never been a huge hugger, and even less so when she was naked.

Then the texture of Mary's clothes against her body started to feel different. Smoother. Warmer. Like...

Mary shifted, frowning, and Kate realized what had happened a second before Mary did.

"What the fuck?!" Mary squealed as she pulled back.

There was a distinct absence of clothing in a straight line down her front, her breasts bare and freshly pressed against Kate's, a few curls of black between her legs. With the absence of the front half, the back of her dress promptly crumpled to the floor. Mary yelped.

"Kate?!" Mary shouted, starting to get hysterical.

Shit, the nanites, it had to be. If they ate away any clothes she wore, it followed they'd have the same effect on any clothes pressed against her, even if someone else was wearing them.

Hopefully they wouldn't have taken root in Mary. Even if her adopted sister's body was surprisingly good, she didn't want Mary to be stuck in the same boat as her. It would raise too many questions.

Speaking of...

"Mary, what!" Kate cried.

"I was going to ask you!" Mary wailed. "What happened to my dress?!"

"I don't know!" Kate lied. "Put something on before anyone else gets back!"