A/N: Delay due to overtime at work, some writer's block, and an overwhelming Outlander addiction. Very thankful to TheHelpfulNeighborLady (AO3) for her work (and patience!) as my beta reader!

It was December before either of them made any real headway with their research. Snape had made a breakthrough. But it wasn't something he had uncovered, so much as the opportunity to uncover something.

'I have arranged to use the headmaster's Pensieve,' he told Harry as they relaxed with tea after an Occlumency lesson. Harry's stomach dropped. Pensieves were rarely associated with good things in his life.

'When?'

'Now.'

Harry sat back, abandoning his tea.

'And you couldn't have told me this earlier?'

'It was not applicable until we finished our lesson.'

Harry sighed, scratching his head. He would be the one controlling the memory extraction, after all. Snape wouldn't have a free-for-all in his head.

'All right, then.'

Snape went and opened a locked cabinet in the back of the classroom and brought the heavy stone basin to the desk, setting it down almost reverently.

'This will work?'

'Not only will this allow us to see the finer details of your accident, but it also circumvents your unwillingness for me to go digging through your mind for the answer.'

Harry folded his arms and smirked.

'You have no idea how enticing you make it sound.'

Snape snorted gently, but no smile actually appeared on his face.

'You know how to extract memories?'

Harry rolled his eyes and drew his wand. He closed his eyes and brought the incident to his mind, remembering how that day had gone. He tapped his wand gently against his temple, and the memory faded as he pulled it away. Opening his eyes, he directed his wand tip to the basin, letting the crinkly, white memory thread slip into the fluid of the Pensieve.

His own twenty-eight year old face was visible on the surface, now, and Harry looked at Snape, feeling awkward.

'I will only be a moment,' Snape reassured him.

'Like hell. I'm coming with.'

Snape gave a long-suffering sigh, and together, they entered the memory.

They arrived in a small flat, and a much older Potter swept past them to put on water to boil in a tiny kitchen. Then he went around the sitting room where Severus and the younger Potter stood, silently directing furniture, cauldrons, ingredients, and books into a temporary lab configuration. Severus was impressed. It was smooth; nothing bumped in mid-air, everything landed gently. Older Potter had done it before, many times. Younger Potter stood back, assessing both his other self and Severus.

Older Potter had three stations set up before the water finished boiling. He made a pot of tea and sat to enjoy a cup. Severus barely held back a growl, and Younger Potter laughed.

'It was a slow morning,' he commented.

'What did you intend to make?' Severus asked, leaving Older Potter to himself in the kitchen, and observing the stations, and the books that had been laid out.

'I was making Blood Replenisher, Mutamorph Potion, and Felix Felicis,' Younger Potter remembered. 'I never did get the Blood Replenisher started.'

Severus nodded. It was the most simplistic, and would only need a couple hours to brew, while Felix Felicis was considerably complicated, and Mutamorph Potion had an extended brewing time, like Polyjuice.

Finally, Older Potter joined them, and began the brewing process for the Felix Felicis. Severus had no criticisms. Older Potter knew what he was doing, just like Younger Potter. But it was boring for Severus, and did not show what he wanted to know. He instead went to browse the bookshelves as Older Potter puttered around at his own pace, enjoying another cup of tea as he went.

After the tea, he came back to begin the Mutamorph Potion. Finally, Severus was interested. He and Younger Potter hovered close over Older Potter's shoulders, reading and committing to memory the ingredient list and process for brewing. They watched carefully as he completed the first phase, and then wandered away to his bookshelves, looking deep in thought.

'What is going on here,' Severus asked, motioning to Older Potter. Younger Potter smiled fondly.

'I was thinking about you.'

Severus could not help the startled look. Younger Potter's smile grew.

'I was thinking about how much you mocked me during classes, and what you would have thought of me brewing potions for work.'

'You mentioned that Horace Slughorn taught you in sixth year,' Severus said, unable to find the voice to continue. His mouth had gone dry. Would he discover the date of his own death?

Younger Potter nodded.

'Dumbledore finally gave you the Defence position.'

Severus let out the breath he hadn't been aware of holding.

Older Potter wandered over at last, smoothing the cover of a ratty copy of Magical Drafts and Potions.

'Here we go,' Younger Potter breathed. They came up behind Older Potter, watching the book pages as he approached the cauldron of Mutamorph base. He cracked the book open, and a trickle of dust came out of the spine.

'Dust. Likely skin cells from you at that age,' Severus explained as Older Potter opened the book to Cure for Boils. A spatter of bright green potion flaked off into the cauldron below.

'Shrinking Solution,' Severus muttered. Why was Shrinking Solution staining the page for Cure for Boils?

'No!' Older Potter shouted at once, snapping the book shut and throwing it aside. The potion glowed an ethereal blue and a plume of smoke exploded upwards, and Older Potter choked on the thick, chalky cloud. He stumbled back, coughing and hacking. His eyes streamed as he caught his breath. It was strange to watch it, unable to assist.

Older Potter wiped at his cheeks hastily, and rubbed his fingers together in front of his face, feeling the texture of the viscous scum on his hands. His sleeves had slid down, exposing his forearms. On his left arm was a series of thick scars on the radial edge... right next to a Dark Mark.

Severus's stomach clenched hard, and he felt rather weak in the knees. Harper wasn't just connected to Harry Potter. Harper was Harry Potter.

Older Potter shut his eyes hard for a few seconds, and then opened his eyes. He did it again. Clenching his eyes shut again, he took a deep breath.

Suddenly, the entire scene changed beneath their feet, and in the exact same position in front of them, stood Younger Harry. He opened his eyes in wide-eyed wonder.

'Mr. Potter, please. We are waiting,' McGonagall encouraged.

Severus looked over at Potter as the memory dissolved around them, and they landed back in his classroom.

'Get. Out.'

Potter looked startled.

'What? Why?'

'Get out!' Severus shouted. 'I do not need a reason! GET OUT!'

Gaping for a moment in confusion – but not fear – Potter left.

Snape did not summon him the entire weekend, and Harry was already feeling completely off-kilter when he arrived in Potions class Monday morning to find Albus Dumbledore sitting in the back of the room.

'The Headmaster is observing classes this week,' Snape announced before everyone got settled. 'You are not to interact with him unless he initiates.'

Harry met Dumbledore's twinkling eyes across the room, and offered a faint smile before sitting next to Draco. The lesson was basic, and they brewed individually. Dumbledore started making the rounds after the brewing was well underway, talking to each student briefly. He stopped in front of Harry's cauldron, and looked into it, nodding and humming.

'Well done, Harry,' Dumbledore commented. 'Have you brewed this before?'

Harry glanced around and saw that even Draco and Hermione were struggling to get theirs on track to be completed in time. Snape was overlooking Crabbe and Goyle's attempts with disgust, and made eye contact with Harry, giving a brief nod.

'Ah, yes sir,' Harry said quickly, 'Professor Snape has been an excellent tutor.'

Dumbledore's eyebrows rose in pleasant surprise.

'How generous of our Potions Master,' he said congenially, before moving on to Draco.

Dumbledore turned up in many of his lessons that week, which perplexed Harry. The headmaster had never done this in all his years at Hogwarts. The only time something similar had occurred was when Umbridge had audited the professors, and there was certainly no precedent for it now. Snape seemed to be avoiding him again, too, which only added to Harry's frustration. He wanted to work on the Mutamorph Potion and a way to get home.

As he went to leave Charms on Friday afternoon, Harry felt the pressure mounting. He had wanted to make a quiet exit over the Christmas holidays. Snape would help his younger self catch up and integrate before the rest of the students returned. So he marched down to the dungeons, and knocked firmly on Snape's classroom door. He held his breath for a tense moment, but the door eventually opened, revealing Snape. Further in the room stood Dumbledore, looking rather grave.

'What is it,' Snape said, irritably.

'Sorry for interrupting,' Harry began hurriedly. 'I just wanted to see if you were still free for... tutoring this evening?'

Dumbledore eyed Snape sharply from behind him, and Snape's eyes narrowed, clearly uncomfortable with being put on the spot.

'Yes. Seven o'clock, Mr. Potter. Do not be late.'

The door closed, and Harry hurried away, uncertain of what he had just witnessed.

Severus closed the door and sighed as silently as he could.

'Another lesson, Severus?'

He turned back to the headmaster.

'Yes. You've seen his skill. He is bored in class.' He walked back to his desk and sat as Albus continued to lean casually on a student desk.

'That is what this is about,' Albus reminded him. 'Why haven't you brought up his gifts before?'

Severus bit back a growl.

'The rest of the staff have been singing his intellectual praises for months now, Albus,' he said. 'I thought you would be elated that I am finally admitting the boy has something.'

'You are his head of house, Severus,' Albus said tersely, standing up straight. 'You need to be directing Harry's care.'

Severus took a deep breath as his thoughts whirled. Albus's observation of various classes – all containing Harry Potter – had been unexpected for most of the staff. He was maintaining innocence by saying his Occlumency lessons with Potter were nothing but extra tutoring; challenging extra assignments to keep the gifted boy busy. But now the headmaster was provoking him and asking why he hadn't requested more for Potter from the other professors.

'I had to be certain,' Severus said softly. 'I had thought...'

Albus frowned, leaning forward slightly.

'Thought what?'

Severus sighed, trying to look shamed.

'I had thought he was an imposter.'

Albus looked thoughtful, leaning back against a desk.

'An imposter.'

'Yes!' Severus insisted. 'I thought the offspring of Lily couldn't-' he swallowed hard, '-couldn't possibly be Slytherin.' He spat the word like an epithet. 'And I thought the offspring of Potter couldn't possibly be that intelligent.' He huffed as though the admission were a weight off his chest. Albus smiled at him.

'Severus, you know I care deeply for you,' Albus said, his eyes twinkling. 'But sometimes, you are mad as a bag of ferrets.'

Severus couldn't help the smile that pulled at his lips, and dropped his head in relief.

'I had thought you were wrong, and the real threat was Potter.'

Albus's gaze hardened.

'I am not wrong, Severus. Quirinus is the real threat. We need to wait for him to expose himself.'

Severus looked back up at Albus.

'He poisoned Potter.'

Albus frowned.

'Why did you not tell me this before?'

'It is still just suspicion. I cannot confirm it,' Severus said, frustrated, standing and beginning to pace. 'I brewed an antidote, and removed the source of the poison. He will not make another such attempt,' he said confidently.

At Potter's urging, Severus had restrained himself. He had binned all the nutritive potions marked for Harry Potter. He had merely cornered Quirrell in a dark corridor, spinning a false tale regarding Quirrell being spotted at Madam Pomfrey's medicine cabinet, and now students were falling ill. The vague threat of you must not be seen was enough to send the small man into stuttering hysterics. Regardless of whether it was an act or not, Severus made sure that Potter's nutritive potions would be delivered directly to Potter from his potions laboratory.

Albus looked vaguely perturbed.

'I wish you had spoken to me about this, earlier.' He shut his eyes and shook his head. 'This was not supposed to turn into a discussion about Quirinus.'

'Of course,' Severus acquiesced. Albus sighed.

'Harry is remarkably like other brilliant students Hogwarts has seen through Slytherin House,' Albus said, giving Severus a look over his glasses. 'We must steer him on the right path, Severus, and make sure he gets the stimulus he needs. The guidance.'

Severus winced at the words, but nodded.

Albus told him he would seek the cooperation from several other teachers to effectively keep Harry busy, and left Severus to his thoughts. How spoiled would everything be if Potter managed to return to his own time and body?

Severus had gone back and forth on whether to break into Potter's mind using Legilimency, but had ultimately ruled it out. It was dangerous, likely would be difficult to find what he wanted, and there was the unlikely chance that Potter would be able to keep him out indefinitely. He would not risk such a humiliation.

So it was after their lesson, when he conjured tea, that Severus attempted to pull the truth from Potter. He had prearranged the tea tray, putting three drops of Veritaserum into Potter's cup. It was almost impossible to tell that it was there, visually. Potter wouldn't know until it was too late.

'So why is Dumbledore watching the classes?' Potter asked, accepting his cup of tea. Severus tried not to watch him too closely, preoccupying himself with fixing his own cup.

'This did not happen in your own time?' he asked innocently. Potter took a large gulp of tea, and snorted.

'Not in all my six years.'

Severus took a sip from his own cup.

'It's because of you.'

Potter looked surprised.

'Why?' He took another large gulp of tea. Another two and he would be finished.

'Surely you are not so dense that you think you are performing at a first year level.' He wordlessly offered Potter a biscuit. It would make him thirsty and more prone to finish his tea quickly. Potter took a biscuit with a nod of thanks.

'Of course not,' Potter said quickly, taking another sip of tea. 'But there is only so much I can suppress my abilities without flat out making intentional mistakes, which at least McGonagall isn't fooled by.'

His words were getting slower. He took a bite of his biscuit and chewed it slowly. Potter drank the rest of his tea to wash it down, and his face finally took on the slack-jawed expression of someone fully under the influence of Veritaserum.

'I feel... tired,' he said, as if confused. Severus leaned forward, clearing the tea tray off his desk.

'What is your full name?'

'Harry James Potter,' he said. 'What's yours?'

Severus swallowed. Most victims felt too hazy to say anything other than the truth that the potion pushed them to tell.

'Severus Tobias Snape.'

Potter's smile grew.

'I knew that already.'

'How old are you?'

Potter eyed him lazily.

'Twenty-eight.'

Severus's eyes glittered.

'What is your occupation?'

These were all questions he knew Potter's answers to; they would create the baseline.

'I am an Auror.'

Severus nodded, sketching a quick note on the parchment before him.

'But,' Potter continued, startling Severus, 'those duties usually take a back seat to my role as Head of the Department of Magical Law Enforcement.'

Severus blanched slightly.

'That is a lofty title for someone of twenty-eight,' he commented lightly.

'Funny, since I got the promotion when I was twenty-seven,' Potter grinned stupidly.

'How did you defeat the Dark Lord?'

'My mother sacrificed herself to save me,' Potter said. 'It created a magic deeper than Voldemort's killing curse, and so when he tried to kill me...'

'When you were older,' Severus clarified. 'How did you... you did defeat the Dark Lord a second time, did you not?' He frowned.

Potter sighed dramatically.

'Well, I defeated him so many times, which story would you like?'

Severus sat back, bemused. Veritaserum usually produced more straight forward answers.

'When you killed him, then.'

'No,' Potter said petulantly, crossing his arms slowly.

Severus sat forward, irritated now.

'How did you kill the Dark Lord?' he enunciated clearly.

'Grindelwald?' Potter asked in confusion. 'That was Dumbledore, you know, and he's only in prison.'

'Potter!' Severus roared. 'You are under the effects of Veritaserum!'

Potter pulled out his wand, and twirled it with a smile.

'Finite Sancus.'

Severus deflated.

'Even without a counter-charm, did you really think you could dupe me like that, Severus?'

Severus glared, but said nothing. Potter stopped twirling his wand and sat forward.

'If I wanted you to know these things, don't you think I'd have told you by now?' he asked, his voice hard.

Severus swallowed hard, maintaining his composure.

'You probably should have thought about whether or not I could throw off the effects of Veritaserum before you secretly dosed me,' Potter said, standing up from the desk. 'After seeing everything I can do,' he said quietly, 'did you take me for a bloody idiot!?' he shouted, his wand pointed at Severus's chest.

Standing, Severus drew his own wand.

'You cannot keep this information from us,' Severus hissed. 'It is completely unethical!'

'Oh, you want to talk ethics now?' Potter laughed, hollowly. 'You had no right!'

'I am trying to save this world!'

'Expelliarmus!'

Severus's wand shot out of his hand, into Potter's. The boy burst through the locked classroom door, Severus following him to the corridor, shouting at him to stop.

He had no choice but to run after him. It was late, and dark, and Severus didn't come across a single person as he chased Potter. The boy was smaller and weaker, and Severus had almost caught up to him before he reached an exit. He surged through the door in pursuit, but Potter was gone.

Huffing, he turned around and around. Where could he have possibly gone? Potter had been flagging, and Severus had been right behind him. There was a whistle in the wind, and it felt like he was punched in the shoulder from behind, an intense pain jarring him forwards off his feet. He hit the ground and his breath left him by force. Coughing, he tried to push himself up, but his shoulder collapsed and he spasmed, a shout of pain escaping him. Growling, Severus crawled up to his knees and sat up, catching his breath.

'Lumos.'

A narrow beam of light shone into his eyes, and he shielded his eyes with his good hand.

Potter ran out of the darkness, his own wand outstretched, pointed at Severus's heart. Severus's wand was lit in his other hand.

'You don't trust me, I don't trust you!' he shouted, his voice breaking with emotion. Severus held his arm up in surrender, not wishing to provoke him, his other arm sagging lifelessly against his body.

'We need the information,' Severus said, struggling to keep his voice calm.

'You're a tosser,' Potter spat. 'Dumbledore has most of the information I know already.'

'Keep your voice down,' Severus said through clenched teeth.

Potter's eyes flashed with fury as he lunged towards Severus, his usual poise lost in his rage. His wand found its way to just underneath Severus' jaw, and the tip jabbed the soft flesh.

'What is it you want to know, Severus?' Potter hissed in a low voice. He stroked Severus's face with a few of his fingers from his other hand, in a mockery of intimacy. Severus flinched away from the touch. 'How I killed Voldemort? How many died to protect me? How many I've killed since?'

Potter recoiled from him suddenly, shaking his head.

'You had no right!' he shouted, turning and walking several paces away. 'There are things I have seen and done that would haunt even you.'

Severus swallowed hard, clenching his jaw as pain surged in his shoulder.

'Potter. Harry-'

But Potter was gone.