Series summary: The TARDIS doesn't always take the Doctor where he wants to go, but it always takes him where he needs to go; Time Lords hold a secret behind their backs, and they have a duty to follow.

Disclaimer: Don't own Doctor Who (or the lines from Forest of the Dead)

Usually, the Doctor loved a mystery. He loved not knowing something, so that he could go through the process of finding out just what that elusive piece of information was. In some ways, he was almost saddened by the ending of a particularly juicy mystery, for once he had the information he could never seek it again; he could never go on an investigation and look for clues and interpret testimonies to find out what he needed to know. The chase, he found, was almost always more exhilarating than the catch.

There were many mysteries surrounding the woman who had entered his life today, but these mysteries were different from all of the others that he had had to solve over his long, long life. These mysteries had an intensely infuriating nature about them, and he wasn't enjoying not knowing nearly as much as he usually did. He wanted to skip to the end, to the moment when he would finally have all the answers, because he needed to know who Professor River Song was.

He had initially let the 'sweetie' comment slide; it was the very first thing that she had said to him, and he had merely assumed that that was how she addressed everyone – this was the 51st Century, after all. But then he had found out that the message sent to the psychic paper had been from her, and that she somehow knew him from his personal future. Even though it was admittedly nice to know that he had a future – and quite a long future, as well, if this woman was insisting that he was 'young' – it was extremely vexing that he didn't know who she was to him.

His curiosity had almost led him to look in her diary, when she had left it lying on the table next to the screen at which he had been working. There was a time, back when Rose had still been living in this universe, that he would have paid careful attention to the changes that he could make in time by knowing things before he should have known them, but ever since he had first met Donna Noble, he had tried to keep thoughts of Rose and the times that they had shared together as far away as possible from his mind – it was just too painful – yet it transpired that such worries were immaterial, for his attempt to see into the professor's diary was prohibited, so River said, by his future self.

Now, as he sat on the floor trying to get his misbehaving sonic screwdriver to work, he was companionless once more. Donna Noble had left the Library – Donna Noble had been saved. The unnerving monotone of the voice of his best friend floated around his head, as well as the emotionless expression of her face on the statue, and he couldn't seem to be able to get rid of it. It was almost distracting enough to make him forget about the mystery of River Song; it certainly distracted him sufficiently to prevent him from hearing her approach him.

"What's wrong with it?" she asked, gesturing to his sonic with a slight inclination of her head.

He was holding the instrument up to his ear, listening to the buzzing that sounded just that little bit off as he held the button on its side. "It's the signal," he explained once he had worked out what was wrong with it. "Something's interfering with it."

"Use the red settings," River told him without hesitation, and the Doctor felt that little bit more irritated at her presence. She seemed so comfortable with ordering people about, and he knew there and then that this woman did not only know him in the future, but in a future incarnation, for in this body, he certainly wouldn't be associated with someone who used that kind of attitude with him. He suddenly found himself dreading becoming the man that the professor knew – he sounded like he was a bit of a fool.

"It doesn't have red settings," he told her curtly, now deeply desiring of being alone – or, rather, of being with anyone other than her at that moment in his personal timeline.

"Well, use the dampers," she suggested instead, not perturbed in the slightest by the fact that he had been so rude to her a moment before – and he didn't like being rude; it didn't fit with his cheery voice.

"It doesn't have dampers," he sighed, looking over his shoulder at River. She had now taken off her gloves and was pulling the future screwdriver from her pocket.

That was yet another mystery of River Song. Why on Earth – or any other planet, for that matter – would he giver her his sonic screwdriver? What was he doing in the future that he didn't need it with him, and that he could afford to let go of it and give it to an archaeologist? And, again, who was she to him that he would trust her with his screwdriver? The more he knew about River Song, the more questions she seemed to pose. One day, he knew, he would understand, but that day wasn't today, and that was just maddening.

"It will do one day," she told him, handing him the future screwdriver. The one in his hand – his own screwdriver, from this point in his personal timeline – shivered in his hand, confirming that this other screwdriver was in fact the same one, just a few hundred years ahead in its own timeline.

The older screwdriver was bigger than his – not that he was overly concerned with such things – and it had a strange loop at one side, as though it was supposed to be held with one finger through the little metal circle attached to the side. He wasn't sure if it was petty to think that it was pathetic; it was a rather childish reaction to what was happening, but then again, if River kept insisting that he was young, then surely he must have had some license to act a little childishly.

The Doctor took the screwdriver and stood up, leaning down slightly so that he could look her in the eye. "So," he began, holding up the future screwdriver to her and bouncing it in his hand as he spoke, "you're telling me that, at some point in my personal future, I just give you my sonic screwdriver?"

River nodded. "Yeah."

The Doctor laughed humourlessly. "Why would I do that?"

"I didn't pluck it from your cold dead hands, if that's what you're worried about," River joked, and the light-hearted humour in her voice made her suddenly seem like a person with whom the Doctor would be willing to travel.

In that moment, he could almost believe that what she was saying was true; but there were still two issues with her: first, she was insinuating that they had not merely travelled together – something about the way that she spoke to him and the way that she felt so comfortable in his presence seemed to suggest that they had a deeper relationship than that of Doctor and companion, which didn't sit well with this current version of himself; and secondly, for all he knew, she could just be the best actress in the universe, for she had not yet provided any solid proof that she was actually telling the truth.

"But how do I know that?" he asked, and he was begging her to understand why he was so cautious, because if she truly knew him in the future, then she would know why he just couldn't believe her.

Yet she seemed to get angry instead. "Listen to me," she snapped, scolding him like he was a child, "you've lost your friend; you're angry, I understand. But you need to be less emotional, Doctor. Right now-"

"Emotional?" the Doctor interrupted her. He had the sudden urge to get back in his TARDIS, go and see his future incarnation and punch him in the face for inflicting this irksome woman on him – if indeed, his future incarnation knew her at all. "I'm not emotional!"

"There are five people in this room still alive; focus on that!" she reminded him, and that was almost frightening.

Not many people understood how the Doctor's mind worked – and surely only the Bad Wolf had ever known exactly how the cogs inside his head turned – but although his companions over the years had always known that he hated to see people die, especially when they were good people, and especially when they died because he had failed to save them, no one had quite grasped the concept of that as it manifested itself inside his brain that accurately before.

How did this River Song know exactly what was pushing his buttons on the inside, when on the outside, all of his anger seemed to have stemmed from the fact that he was frustrated at not knowing who she was?

"Dear God, you're hard work young!" she sighed exasperatedly, and there it was again – just how far in the future did he know this woman? How long would he have to wait to find out? Yet his impatience got the better of him, and he decided to at least try to find out now rather than wait all that time until that point, somewhere in the future, when that question would finally be answered.

"Who are you?" he demanded of her for the umpteenth time since her and her expedition had arrived in the Library, taking a step closer to her and leaning over her a little more.

But River wasn't afforded the opportunity to rebuff the question once again, because they were both interrupted by the man who was the reason that they were all here in the first place.

"Oh, for heaven's sake!" Lux cried, walking slowly over to the two of them. They both turned to look at him. "Look at the pair of you! We're all gonna die right here, and you're just squabbling like an old married couple!" Lux turned away then, his rebuke finished, but the damage was done.

The air between the Doctor and River changed, and a palpable tension that was significantly more uncomfortable than the one that had accompanied their arguing the moment before filled the room. When the Doctor turned to look at River, and River turned to look at the Doctor, there was a distinct look of fear in her eyes – as though he had just broken his future self's rule and stumbled across something that was written in that book of hers…

Surely not.

The Doctor didn't dare to think that that could possibly be true, and so, when a distraction presented itself in the form of River speaking softly to him, he grabbed hold of it and ran with it, leaving the disquieting thoughts behind him in the dust.

"Doctor," the professor began slowly, "one day I'm going to be someone that you trust. Completely. But I can't wait for you to find that out." River hesitated, and the Doctor felt an anxiety at what she was about to do. How much of a spoiler was she going to give him? He had spent the entire time since she and her fellow group of archaeologists had arrived at the Library trying to figure out what the spoilers she presented to him really were, yet now that he was faced with the reality of actually finding some of them out, the panic he felt was intense, and he found that he really would rather be left in ignorance.

"So I'm going to prove it to you," River continued, "and I'm sorry." She reached up to his chest, placing her hand between his two pounding hearts – and surely she must have felt how they were beating out drum and bass against his ribcage – before she whispered tearfully, "I'm really very sorry."

River took a deep breath to steady herself, and then three things happened.

First, River leaned into his ear, having to stand slightly on her tip-toes to reach up to it; second, she told him to look closely at her; and third, she whispered his name. Not 'Doctor'; not even 'Theta': his actual name, the one that he had not even spoken himself for centuries.

He was so overwhelmed by the shock of having heard his name spoken aloud for the first time in he didn't know how long – especially when it sounded so natural falling from her lips, and nothing like the dangerous weapon that he knew it to be – that he almost forgot to pay attention to her command when she stood back from him.

At first, he thought that she had lost her marbles; what exactly did she want him to 'look closely' at? There seemed to be nothing that distinguished her as different from any of the other people on the expedition. Yet he did as she asked, and suddenly, all became clear.

The Doctor almost kicked himself for not noticing it sooner; then again, the entire Library was shrouded in darkness, and he and Donna had only been in the light when they had first arrived there. As it was, the room that they now found themselves in was dark enough for him to have to strain his eyes to see them.

Either side of Professor Song were two shadowy shapes, impossible to see when it was too dark and, he supposed, impossible to see if you were not strong enough to. None of the other members of the expedition would have noticed that they were there; they were all human, after all. Even now that the Doctor could see them, he still had to look incredibly closely before they began to resemble anything other than shapeless blobs (though his utter disbelief may have been playing a part in his difficulty to distinguish their true appearance).

Yet as he stared, and as he became more aware of exactly what he was seeing, he could deny it no longer.

River Song had wings.

They were not true Time Lord wings, however; they were wispy, shadowed, as though they were made of air and smoke rather than bone and skin and feathers. They didn't appear to have a colour, and it was easy even for him to see straight through them as though they were pieces of stained glass hanging suspended in mid-air, though under more careful inspection, he found them to be of dark colouring: black and grey – which is probably why he hadn't been able to see them when they had been in the shadows.

He reached up to them, a part of him still not quite believing that this could actually be happening. They looked so flimsy, so illusory, that they couldn't possibly be real.

Yet they were. His inquisitive fingertips touched on feathers; the wings were tangible, just as his own were. He felt his eyes widen as he drew his fingers across them, unable to comprehend how they could possibly be there.

River Song was not a Time Lord. There was no way that she could be; all of the Time Lords had been destroyed with Gallifrey, and the Master had died in his arms aboard the Valiant. Even if there was a Loom left in existence somewhere in the universe – which the Doctor sincerely doubted – there was no one other than him who would have been able to use it to create a new Time Lord.

Yet, he thought with a jolt of fear, maybe that was who River Song was: maybe she was his daughter, like Jenny (though Jenny had been created with human technology that itself was not sophisticated enough to create wings for her, and besides, she was gone). Maybe his future self had found a Loom – or created one, for all he knew – and made this River Song to accompany him and finally end his loneliness.

River certainly didn't know Donna personally – though she seemed to know of her – so it was perfectly possible that the Doctor's foolish future incarnation would create another Time Lord to keep as company if he lost Donna (when he lost Donna, it would seem, and even though she had been 'saved', there was a part of him that still refused to believe that Donna Noble dies in the Library). It would certainly explain why he wasn't allowed to look inside that book of hers, and why he would give her his screwdriver.

But a Loomed Time Lord would not have such wispy wings. They would be fully formed, like his own, rather than smoky ghosts of pinions protruding outwards from the spine, and the Doctor found himself deeply sceptical that River Song had two hearts beating in her chest. Besides, if the Doctor really did acquire a Loom in the future and create another Time Lord, he would surely not have let all of the effort that it would have taken to do something like that go to waste by allowing his child to become an archaeologist.

And so, as River chuckled softly at his amazement at her wings, he found himself back to square one with regards to the mystery of this professor.

"You know, that's not fair," she breathed, the corner of her mouth twitching up in a small smirk. The Doctor's brow furrowed, but his confusion dissipated when she gently removed her hand from his chest and reached up to his own wing, laying her palm flat against it and giving him a small chuckle.

A moment passed in silence before they both lowered their hands to their sides once more.

"Are we good?" River asked quietly, but the Doctor forgot to answer straight away, for he was still caught up in the amazement that he was not the only one who still had Time Lord wings in the universe. "Doctor?" she repeated, and he was finally ripped out of his reverie. "Are we good?"

He nodded quickly, gulping slightly. "Yeah, we're good," he breathed, frozen in place by everything that had happened in the past few minutes.

"Good," River said with a touch of finality to her voice. She held out her hand for his future self's sonic screwdriver, and he placed it in her expectant palm before she turned back to the members of her expedition who were still alive.

The Doctor followed her with his eyes, not knowing exactly what to think. He still desperately wanted to know who River Song was, and how she had wings – because no human had wings; not even the Bad Wolf had had wings – but they had come to a truce, and he now realised that, if he in the future had trusted her enough to tell her his name, then he in the present could lay to rest the million and one questions revolving around his head.

He still wanted to know who River Song was, but for now, it could wait.

"Now, you see, the thing about my screwdriver…"

A.N.: You will have to wait for the next one, I promise. I haven't even started it yet. But I can tell you that it will be set during Journey's End, and that there are only two more Ten era fics left (this time round, anyway).

UPDATE 09/07/14: Next part of the Angel!Verse, Scars, is up now.