AN: So basically, this is a response to a prompt over on livejournal. This was the prompt:

Darcy lives/works in the Tower and while people like her, no one thinks that there is something off about her. Which is that she is a Time Lady who has just been taking a break from Time and Space and has decided to live through the Avengers Age on Earth that she's read about so much.

Then Tony once again does a routine upgrade of the security parameters which knocks out the perception filter that Darcy has and someone notices that she has two hearts. Cue chaos.

Shipping isn't mandatory but I prefer Clint/Darcy or Loki/Darcy.

So this is my response! I hope you enjoy!

Disclaimer: I don't own Avengers or Doctor Who

When Tony once again did a routine upgrade of the security parameters of Stark Tower, as was his habit when he was feeling particularly bored or paranoid, he noticed something odd. And when Tony Stark notices something odd, he likes to investigate. It made him feel all detective-y, which was great fun for the ever bored genius.

This odd something, however, was medical, which meant he needed to bring someone who know "medical" quite well. Fortunately for him, he had a science buddy by the name of Doctor Bruce Banner, who was well-versed in the medical field. Excellent.

A/DW

Darcy Lewis felt something was off. She felt it in her bones, in her body, in her timeline. She had a sinking suspicion that her hidden identity was under the threat of exposure, but this couldn't be. Not even Tony Stark had the technology or the brainpower to overcome her inherent genius as a Time Lady. No, she was definitely imagining things.

A/DW

"Well, Dr. Banner, what do you think?"

"It is definitely a medical phenomenon, if that's what you are getting at."

"Yes, but how is it possible? Medical lab experiment gone wrong? Mutant? Alien? Fell into a vat of radioactive potato skins?"

"I very much doubt it's the last one, Stark. But any of the others seem plausible, especially now that we know aliens exist."

"So, what should we do? Any suggestions Dr. Banner? JARVIS? Dum-e?"

"To be honest with you, Tony, I think we should take this to S.H.I.E.L.D."

"Nah. I don't like that idea. Let's poke her with a stick! Or shine bright lights in her eyes. Maybe we should try-"

"Stark, you're missing something."

"What's that, Jekyll?"

"Jekyll?"

"Yeah. You know, Dr. Jekyll and Mr. Hyde. Mild-mannered scientist, crazy alter-ego monster-beast thing."

"I got the reference. While the appearance of two hearts is amazing, the lack of lungs is quite disconcerting."

"No lungs? Yeah, okay. S.H.I.E.L.D. it is. But I'm not bringing it up. I'll get an agent to do it. I wonder if there are any newbies…"

A/DW

It was most definitely not Probationary Agent Carl Johnson's day. He'd thought it odd when he was asked to deliver some paperwork to Stark Tower. After all, dealing with the Avengers, in any aspect, was a job for any of the higher ups, not a green agent whose sole job up till now was shadow the coffee runner. And while he thought it was odd, he'd been quite excited when he got this job. Now he knew better. He knew why he'd been sent. Mr. Stark had wanted a newbie and was probably going to watch his interaction with Director Fury through hacked security feed. Probationary Agent Carl Johnson was definitely reconsidering his career choice.

It was time to tell Director Fury about Mr. Stark and Dr. Banner's discovery.

"Director Fury, sir?"

"What is it Agent?"

"Oh, well- um…"

"Spit it out, Agent."

Johnson quaked under the intense power Fury contained in his covered eye. Yeah, he really hated Stark right now.

"It's just, sir, Mr. Stark has come across something…" He trailed off.

Fury raised his eyebrows in increased impatience, "something…"

"Weird. Sir."

"Weird how?"

"Well… it appears that Ms. Lewis has, um, Ms. Lewishastwoheartssir." This last part came out in a frantic, hurried jumble.

"Agent?"

"Yessir. And also, uh, no lungs."

"No lungs?"

"Yes. Absolutely none whatsoever. Mr. Stark and Dr. Banner have sent a file. With findings… and stuff."

It was no secret that it took a lot to surprise the unflappable Director Fury, but Probationary Agent Carl Johnson knew without a doubt that he'd done just that. And he wasn't exactly sure how he was supposed to handle this. He really hoped he didn't spontaneously combust with the way the Director was staring at him. Had been staring at him. For the last five minutes. Without blinking. Oh dear.