A/N: As of right now there are no actual plans to continue this, although I rather like this universe. I have vaguely sketch-planned a rewritten Battle of New York but not to the extent of writing it, so this will be marked as complete although rewriting the entire Avengers movie is a tantalising thought (read: I am almost stupid enough to do that).

Anyone else think that the title of this one shot is quite worrying?

Captain Jack Harkness, Agent of SHIELD

Steve had seen him at the SHIELD base a few times. He'd caught the super-soldier's eye, because that old uniform was at once completely familiar and jarringly out of place in the modern base. It was the 1944 US Air force uniform – a captain, as it happened – and Steve had wondered briefly if maybe he wasn't the only one who'd wound up out of his time. Maybe someone else had crashed their plane into the ice, and well – no, they would have told him. Perhaps the guy was a re-enactor, or maybe some divisions still wore the old uniforms. Or maybe he was just a bit eccentric. SHIELD attracted the eccentric ones.

His face was familiar too, vaguely, although Steve had never been able to put a name to it. He hadn't thought too hard about it, though, having had several other things on his mind.

Then, one day, Fury had called him into a briefing and started to talk about something called the Avengers Initiative and introduced him to Captain Jack Harkness. Steve rose politely to shake his hand, and the man gave him a ridiculously cheesy, propaganda-poster grin, and said 'A pleasure to meet you, Captain,' in a voice that sounded like it meant something else entirely, and Steve realised where he'd seen him before.

It had been back in the War, and he had been dragged along to some stupid dance because someone somewhere had decided that Captain America needed to get out more (and they didn't really care what Steve Rogers thought). Seventy years ago, but for him it was only a few months. And Captain Harkness had been there, smiling and dancing with all the girls and, well, some of the guys too, and naturally Steve noticed him – it was hard not to.

'You too,' Steve said automatically, and then, 'Actually, we've met. Seventy years ago, at a dance in Denver. You probably noticed me. I was the one dressed as the American flag.'

Captain Harkness met his gaze with a frank and friendly openness that told Steve instantly that he was lying, and said, 'Of course. Captain America's hard to miss. Denver, huh?'

'Some event to raise troop morale,' Steve said evenly. 'You're looking good for a man who fought in the War.'

Captain Harkness grinned. 'You can talk. We should form a club.'

Steve smiled tightly and Harkness sat down casually. 'Heard about your plane,' he said with an easy smile. 'Stuck in the ice, that sucks. Slow, too. I once spent a thousand years in a volcano, but at least it was warm. Ice, not my idea of fun.'

Steve sat too, suspicion, scepticism and disbelief crowding into his mind. 'Captain Harkness, do you expect me to believe that you're over a thousand years old?'

Harkness grinned. 'Captain Rogers, do you expect me to believe that you're a superhero who fought in World War Two?'

Steve conceded the point with a nod and turned to Fury, looking for clarification.

'Captain Harkness has worked for us for twelve years. We have held a file on him for over 100. He was around at this agency's inception,' Fury said coolly. 'He does not have the mutant gene. He has not been exposed to gamma radiation. He is genetically nearly human, although the unidentified patterns of DNA have no significant impact at a cellular level. Physically, he is an ordinary man.'

But if he's on SHIELD's radar, he's no such thing, hung unspoken in the air. Fury looked as bland and neutral as ever. Harkness was grinning, although it looked a little forced. Clearly, some of the testing hadn't been voluntary.

'Jack Harkness cannot die.' The words fell into a pregnant silence. 'He ages, at a billionth of the rate of an average human. But he cannot die.'

'How?' Steve asked blankly. He couldn't bring himself to be surprised at anything since he'd woken up in the future.

Jack's eyes were hard. 'There was a girl, a rip in the fabric of time and space… You know how it is.'

Steve did not enquire further, sensing that it was a sensitive topic.

'And he has been recruited to this… initiative?' the soldier asked Fury.

'That's right. Immortality is a useful talent around here.' Fury looked from one to the other. 'I guess you have a lot to talk about, but I need you in Germany. Coulson will brief you. You're taking the jet.'

'Who's piloting?' Harkness asked.

'Black Widow.'

Captain Harkness winced. 'That… isn't Agent Romanoff, is it?'

'You know her?' Fury asked.

'Let's just say… she isn't too fond of me.'

'Captain Harkness, Agent Romanoff isn't too fond of anyone. She's an assassin.'

'Yes, but… she really doesn't like me.

That might have been an understatement, Steve considered, as he watched Black Widow pinning Harkness to the floor of the jet with a gun in his face before Coulson was done introducing them.

Within moments, everyone on the plane except Harkness was holding a weapon. Harkness didn't seem too worried – almost bored.

'Agent Romanoff,' Coulson said steadily, gun pointed in the direction of the combatants, ready to fire at whoever posed the biggest threat. 'Explain.'

'This… man… interfered with a SHIELD sanctioned mission, let a target escape, and sabotaged an operation,' Romanoff gritted out. 'The only reason I haven't put a bullet in his skull is that it didn't seem to take last time. Sir.'

'Captain Harkness,' Coulson said in the same tone. Steve was oddly reminded of a teacher sorting out squabbling toddlers. But with more guns.

Harkness held up his hands. Or at least, he began to, before Romanoff pulled back the safety on the gun in a menacing fashion. 'OK, OK! Look, if it helps,' he said in a slightly strained tone, 'I don't actually remember that, which means I was drunk out of my mind –'

'Not entirely implausible,' Romanoff muttered.

'– or someone drugged me –'

'Widow,' Coulson said questioningly.

'Not guilty, Sir,' she said blandly.

'– or I haven't done it yet.'

There was a beat, and then Coulson sighed and motioned for Romanoff to lower the gun, putting away his own. 'You know, it says a great deal about the nature of my job that I actually believe you.'

'You said Agent Romanoff didn't like you,' Steve said suspiciously. 'Why would you say that if you don't remember any of this?'

Harkness grinned. 'I guess that hasn't happened yet either.'

The flight to Germany took a while. Steve sat in the back of the jet, turning the shield over in his hands idly.

'You know,' he said to Harkness, who was sitting across from him, 'There are times when I look at my life and wonder what on earth is going on. This seems to happen a lot more when you're around.'

Harkness grinned. 'It's only going to get better, kid. Wait till you meet the rest of the initiative.'

'Why, who else has Fury signed up?'

Jack grinned in a faintly worrying fashion. 'They aren't signed up. Yet.'