Thank you to everyone who has read, favourited, alerted and reviewed this story. It all means a lot, so thank you very much! I hope you continue to enjoy the story.

Chapter Nine: The Mark of Cain

Noiselessly, Severus placed the diary on the headmaster's desk and slid it under the older man's nose. It was hard to deny the rising sense of triumphalism he felt in presenting this darkest of objects to Dumbledore, despite the fact it was still fully in-tact. It felt like he had achieved something, or rather, proved a point. That regardless of what he had done in a past life, he had avoided falling down the same pitfalls this time around. That maybe, just maybe, he was in with a chance of redemption after all. "The diary, sir, as promised."

Dumbledore picked it up his right hand, turning it over so he could inspect it fully. He tilted it toward the morning light spilling through his windows, frowning intently as he fanned through the blank pages from beginning to end. "Excellent work, Severus. Most excellent, indeed. Now, sit."

Tea had been made and a cup slid itself toward Severus as he settled in his familiar place before the desk. He took the cup and watched over the rim as Dumbledore rifled through the pages, once more. Once that was done, he placed it flat on the desk and pressed his palm into the leather binding, his bright blue eyes closed in concentration. Eventually, he took out his wand and murmured an incantation Severus could not hear. Whatever it was, it caused the diary to open and the pages to shiver as though a sudden breeze had swept through the office. It's ancient, yellowing pages seemed to glow for a moment before the light they made faded as quickly as it had appeared.

Then, the headmaster sat back, seemingly satisfied. "As I feared, this is a Horcrux. I shouldn't be too surprised, it's not as though I had no forewarning. All the same, I had hoped for a more positive outcome."

"At least we now know for sure, sir." Severus glanced over the headmaster's left shoulder, to the patch of wall where the sword of Godric Gryffindor was on proud display in its old glass cabinet. The ruby caught the morning sun, turning as bright as fire as it soaked up the early heat. He put down his cup and continued, "we used the sword to destroy them last time, sir. Surely we can just do that now?"

He no longer had the memory of getting that sword to Harry Potter, but he knew rightly that he had done exactly that. Alas, Albus looked rather more uncertain. "In the future, you said the Chamber of Secrets had been opened and the basilisk within slain. Was it slain using the sword?"

"Yes."

"Then that is why the sword was capable of destroying Horcruxes, Severus. The blade had been infused with basilisk venom." That earlier sense of accomplishment had drained from the headmaster, replaced with an older and wearier look of resignation. After a drawn-out silence in which Dumbledore appeared to be studying the floorboards at his feet, he continued: "Defeating Voldemort was never going to be safe. Or easy. And the next step in our mission is even more dangerous than the last, Severus."

He had already guessed where this was going. "You want me to open the Chamber of Secrets and use that sword to kill the basilisk? Summer's coming, so at least it can be done without endangering anyone else."

"If only it were as simple as that."

Severus felt the cold weight of an unexpected obstacle settling in the pit of his stomach. "Oh?"

"You did a remarkable thing the other day, Severus," Albus continued. "I don't mean gaining entry into Malfoy Manor, either. You set aside your own considerable personal grievances to join forces with an enemy. No doubt, Miss Evans, played a significant role in proceedings. But only you and James Potter could have made that final step and do what needed to be done. You know, Godric Gryffindor and Salazar Slytherin themselves once embraced each other as brothers –"

"Steady on, headmaster," Severus cut in with an indignant laugh. "I wouldn't go that far."

Dumbledore chuckled. "Quite right. But you misunderstand me, Severus. However, surely you see what I hint at? That the day Gryffindor and Slytherin severed ties, a great well of enmity was opened between their two houses that exists to this very day. Any step taken towards healing that centuries old rift, therefore, can only be an extraordinary thing."

"I suppose so." Severus wasn't quite yet willing to admit it, nor stretch his imagination far enough to envisage any real benefit of working with Potter besides convenience. "Anyway, I've been friends with Lily since were little and she's a Gryffindor. It's not like we all hate each other just because an old hat put us in rival houses."

"But Lily is not your enemy, Severus, and she never has been. Since, by your own admission, your friendship began long before you were sorted," the headmaster insisted. "As such, reaching out a hand of – if not friendship – then cooperation to James Potter carries with it a far greater weight of significance."

Still somewhat begrudgingly, Severus shrugged. "Yes, I see sir. But I did what had to be done. For the sake of the future."

"I can see you're intent on dragging your feet over what this all means, Severus. Which makes me even more certain on the next course of action. The Chamber of Secrets. Only a true Gryffindor can wield that sword and neither you nor James Potter can open that Chamber and take on the basilisk alone."

"I'm happy to work with him again, sir," Severus replied, quick to assure the headmaster. "If this is what it takes, I'll meet him and Lily again straight after we're finished here. We'll plan it all out together just as we did before."

Dumbledore looked happy again. Blue eyes twinkled from beneath snowy eyebrows, peering at him from over gold rim spectacles. "You must all return home on the Hogwarts Express next week. It is important that you're all seen. But as soon as you're ready, floo your way back. As we agreed, this will only be safely done when all the students and staff are away for the summer."

Already a plan was forming in his head. They would need mirrors, the sword and plentiful supplies of the Mandrake Restorative Draught just in case any of them did get zapped by the powerful gaze of the basilisk. Although it was a tricky potion, he knew Lily and he would work on it together.

"Purely by coincidence, I had Professor Sprout working on a fresh batch of Mandrakes," said Dumbledore, averting his gaze to the ceiling. "Funny how life works out, don't you think?"

"Quite," Severus drily agreed. As was often the case, he could not escape the feeling the headmaster was already several steps ahead of everyone else. That he was being guided down a path of Albus's own choosing, of which he was only dimly aware of the next few steps ahead. Nevertheless, he knew it was pointless to try and get more out of him now and so changed the subject. "Sir, was we left Malfoy Manor last night, we walked straight into a Death Eater's meeting."

Dumbledore now looked gravely concerned. "Do you think you might have been seen?"

"No, sir. If we had been, we would all three be dead by now. Since the Dark Lord and Lucius Malfoy were talking right in front of us."

"Goodness, I can quite imagine." The headmaster quickly returned to his usual whimsical self. "Did you overhear anything of import?"

"It sounds like they were planning a hit on the Minister, sir."

"If Harold Minchum hasn't survived three assassination attempts before breakfast, then he considers it a very dull day, indeed. Nevertheless, I shall see to it that he is forewarned."

Severus gave another dry laugh, but his mirth was short-lived. He soon lapsed into silence, averting his gaze as he recalled the conversation he had overheard between the Dark Lord and Lucius Malfoy. The conversation about him, and about his classmates. James had mockingly referred to it as his "date with Malfoy" and Lily had been polite enough to let the matter drop, at least at the time. But it came as another punch-in-the-gut reminder that he had, once, truly been a Death Eater. And now he did not know how to bring it up with Dumbledore.

Yet, as ever, the old man was worryingly perceptive. "I sense there is more you wish to tell me, Severus."

"Yes," he replied. "The Dark Lord instructed Lucius Malfoy to summon me over the summer holidays. To 'guide me', he said."

"Even in this lifetime, it would not be for the first time. Unless I am much mistaken," Dumbledore replied.

"I know, sir. Surely, you can understand that everything has changed since then." Severus had not meant to sound so defensive and now backed down, relaxing his shoulders before he could tense up too much. "Forgive me. It just reminds me that … It reminds that I was never on the side of the angels, sir. That I did things for which I had no right asking for forgiveness."

It wasn't that he had killed anyone. Merely watched, as other people did the killing. Which, in his eyes, was much the same thing. He had attacked people, gone on raids. He tried to rack his memory, recalling any moment in time in which he had truly believed in all the blood supremacy nonsense. But he never did. Mudblood was just an empty insult he threw around just to see the looks on the victim's faces. It was just a weapon he did not care about. A word, the weight of which he was deliberately and wantonly ignorant of. The shame of it had lasted a lifetime, the stigma he had carried even into this life. The dark mark burned on his arm. His own personal Mark of Cain, telling of his infamy to all who beheld it, warning others to keep their distance. Without realising what he was doing, his hand gripped the spot where it was, digging his nails into the sparse flesh.

All the while, Dumbledore was looking at him from across the desk, holding him in an almost paternal gaze. When he spoke, he did so softly. "Severus, you are not a bad person. Whatever it was you did in your old life has little to no bearing on this one. Consider, if you will, that you could have woken up in the Hospital wing knowing what you know, and kept your mouth shut. You could have had James Potter and even Sirius Black expelled, lived your life all over again, and changed nothing. It would have been so easy. Instead, you chose what is right."

"I know, sir," he replied. "But it all still happened, didn't it?"

"No," Dumbledore retorted. "Because it hasn't happened, Severus. Don't you see? How can something that happened to you at eighteen still be real if you're only sixteen. It has all un-happened."

Still none the wiser, Severus countered: "My mark. My trace."

The absence of the latter and the presence of the former made no sense if it had all 'un-happened'. Regardless of what Dumbledore said, he was certain at least some of what happened in his other life was relevant. And not just his knowledge of the war.

"Not everything in life makes sense, Severus," Dumbledore said, at length. "Nor can I promise you answers. But you are not a Death Eater. You are just a student again. I would suggest you make the most of it."

"I shall," he said. "But would you like me to answer Lucius's call?"

"That's up to you, Severus."

"I think I could find out useful information. Whether real or not, it's what I did before and it's what I know how to do."

"Then do it," Dumbledore answered. "But do be careful, won't you? Keep that mark hidden. Don't be rash or hasty."

Severus nodded. "Should I tell James and Lily about Horcruxes? It only seems right now that they've helped me find one and they're about to risk their necks to destroy it."

"Yes, I think, now we know for sure, it is time to tell them everything."

Relieved, Severus prepared to leave. Albus had the diary and it was time to move to the next stage of the mission. Destroy the damn thing. Yet, as he rose, one more thing occurred to him. "Sir, I keep dreaming about a cave."

He'd had the dream again the night before, as he slept with the Horcrux under his pillow. It had been more vivid than ever. The black water, the oppressive cold and the shimmering green light rising from unseen island far in the distance.

"Sometimes my father is there," he continued. "He's going to leather me, so I'm running away. I hit the water and all this inferi rises and drags me down. And after everything that's happened, I'm not prepared to dismiss it as just a silly dream."

He had been afraid, before, that Dumbledore would do just that. Dismiss it as the fraught workings of a fevered and confused mind. Instead, the old man looked perplexed. Even troubled. He repeated certain descriptors to himself, mouthing the word 'cave' twice. When he spoke, however, it was in the manner that suggested his concerns had been noted. They would not be forgotten. But for now, they should not be fretted upon. "Don't worry about it, Severus. All in good time."

"Where were you last night?" The sound of Mary's voice jolted Lily out of her reverie. From where she had been gazing vacantly out of the common room window, she gave a start and jerked her head round as her old friend flopped into the seat opposite her. "Don't deny anything funny was going on either, Missus. Two am I woke up at and found your bed empty, you dirty stop-out!"

"I was at Slughorn's party, you know that," replied Lily, more defensively than she had intended. Besides, she hated lying and this wasn't entirely a lie. Containing enough truth to prevent her from turning beetroot red, she continued: "It all got a bit out of hand, you see. Adrian Pucey got blind drunk on firewhiskey he snuck into the school and the rest of us had to look after him."

Mary looked her dead in the eye for a moment, then let out a loud laugh. "Oh, my days. I heard about that. I thought it was just kids making stuff up." She paused, straightening out a lock of her tightly coiled hair and then releasing it, watching it spring back into its natural form. "I think I might be starting to regret not going to Old Sluggy's parties when I got the invite, now."

"I wish you had come, Mary," Lily replied, meaning it. "Severus is the only other person who attends that I really know –"

"Exactly, and I'm not playing gooseberry to you two all night. Anyway, speak of the devil himself, Lil. Your favourite pet monster gave me a message. He wants to you and James Potter to meet him down in the Potion's classroom." The curl sprang back into place; Mary turned her dark brown eyes to Lily. "Sounds like a trap if you ask me."

"Oh, don't be silly Mary!" Lily got up and slung her bag over her shoulder, getting ready to leave. "Catch you later, okay."

Even by the time she finished her sentence, Lily was already half way through the portrait hole. She had no idea where James was, but continued making her way down the stairs as she kept an eye out for him anyway. As she went, however, it was the diary that occupied her. She hadn't been able to stop thinking about it since she had seen what it could do and she still couldn't fathom what it all meant. And now, the morning after the night before, she felt like she had thrown herself into the firing line knowing only half the story.

"Remus!" she called out to her fellow fifth year the second she saw him. "Remus, where's James?"

He looked rough. It was the eve of the full moon and it was written in the lines already forming on his prematurely-aging face. Nonetheless, he greeted Lily with as warm a smile as ever he did. "Quidditch practise. You want me to get him?"

"Please, Remus. Tell him to meet me in the Potion's classroom," she said, already hastening past him. Feeling bad for not stopping to talk properly, she called back over her shoulder. "Thanks, Remus. Love you!"

"Sure you do," his voice trailed in her slipstream.

She reached the dungeon in good time, her progress made quicker by the fact the school was starting to empty. Those who didn't take the train had already left, most of the rest were in class or lazing by the lake. Thus, she slipped past the Slytherin and Hufflepuff common rooms uninterrupted and reached the near-empty Potion's class in good time. Opening the door, she found Severus already hard at work.

"Hey!" she greeted him cheerfully, crossing the room at a leisurely pace. "Mandrake roots. Mint. Valerian root…" she listed off the ingredients she saw, already neatly chopped up, beside his cauldron. Then she peered inside to see what he had so far. "Already turning a nice shade of minty-green. So, you're making a Mandrake Restorative Draught?"

She looked up at him, smiling in anticipation. She always enjoyed guessing what potion he was making, always feeling the same rush of excitement when she guessed correctly.

"Got it in one," he replied. "And we're going to need it too. A lot of it."

"Oh," she replied, curiously. She knew this was her cue to fetch a cauldron – having neglected to bring her own – and get brewing herself. She didn't mind, though. She loved brewing potions with Severus and it felt like forever and a day since they had last done so. Once she found a school cauldron that was still in relatively decent condition, she set up on the bench at Severus's side and lit the flame with a wave of her wand. "So, are you going to leave me in suspense over the fate of the diary?"

He made a face. "That diary is the gift that keeps on giving. But, did you find Potter on the way here? Because I need to explain this to both of you."

Right on cue, hurried footsteps echoed down the corridor outside, stopping sharply once they levelled with the door. Moments later, a flushed in the face and breathless James Potter shouldered his way through the door. "I got your message," he said, wiping a smudge of mud from his nose. "So, the diary. Have we destroyed Tom Riddle's soul yet?"

Ever since he found out the Dark Lord's real name was 'Tom', James had taken great delight in using that instead the more fearsome monikers the darkest wizard himself preferred. And Lily couldn't blame him. Meanwhile, he drew a stool up to the opposite side of their bench and perched himself on top of it, looking from Lily to Severus and back again. From the bench along the wall, the twisted face of a dead mandrake plant peered out from under a crushing slab. She wished Severus had covered it up.

"Yeah, about that," said Severus, almost apologetically. "Potter, remember that time you almost lured me to my death during Remus's transformation?"

Lily wanted to kick him for dredging that up again. But now that he had, she wanted to focus on making sure James didn't overreact. He had turned red again and she could tell he was biting his tongue. All the same, she braced herself for danger. However, it was Severus who continued his explanation, doing so quickly before the other boy could get mortally offended. "Well, what we need to do next is a little bit like that. Only, a hundred times worse. You both know the story of the Chamber of Secrets, yes?"

"No," said Lily.

James looked intrigued. "Wait, I remember … Salazar Slytherin was supposed to have made it when he left the school, right? It came up when we were doing research for the Marauder's Map, but we never found it. We searched everywhere."

Lily was still lost. "Spare a thought for this Muggleborn and start from the beginning, you two!"

James nodded to Severus, a signal for him to start talking as he and Lily listened.

"You know already Godric Gryffindor and Salazar Slytherin were once the best of friends, but had a bitter falling out. Gryffindor wanted to take all magically able people into the school. Slytherin wanted only purebloods. So, in revenge, Slytherin built a huge chamber deep underground. Way deeper even than the lake. And the secret hidden within that Chamber is a giant basilisk. Just one look in its eyes will kill you. Look at it indirectly, and it will merely petrify you."

Lily groaned. "And we're making a Mandrake Restorative Draught for a reason, aren't we?"

Severus had that rueful, regretful little smile on his face again. "Look, if you two want out –"

"Are you kidding?" James cut in, eyes ablaze. "If you think I'm letting you two go off basilisk hunting without me, you've another thing coming." Then he calmed again, taking off his glasses and wiping them on the bottom of his shirt. "How is this related to the diary, though?"

"The diary is a Horcrux." Severus answered softly, his voice like silk. He then stopped, finished stirring his potion counter-clockwise and took out his wand to cast a silencing spell. Then he locked the classroom door from within and dropped the blinds. Now Lily was nervous. She had no idea what a Horcrux was and neither did James if his expression was anything to go by. But it was clear Severus was unnerved by them. Anything that made him as skittish as this couldn't be good.

"A Horcrux is made when a dark wizard commits murder. A fragment of their soul splits away and they encase it an object to be kept safe. Then, if their body is destroyed, they won't die because their Horcrux can be cracked open and their body regrown from the soul fragment within. We can only destroy Horcruxes with basilisk venom."

"And Salazar Slytherin was kind enough to leave a basilisk deep under our castle," said James. His face was pale now, all that youthful ebullience gone.

Meanwhile, the enormity of the task was opening up to Lily; expanding in her mind like the view from a mountaintop. "You-Know-Who can't be killed until the Horcrux is destroyed. If that's the case, we need to do this – I'm not backing out, no matter what."

Yet again, Severus looked sheepishly apologetic and a cold sensation of dread closed over Lily as he spoke. "You say destroy 'the' horcrux, like there's only one. The thing is, you see –"

"Oh, shit!" James cut in in disgust. He was on his feet, running his hands through already rumpled hair. "Of course there's more than fucking one. How many people has that animal killed already? How many fragments of that creature's soul are out there?"

"I think we should worry about that later," Severus cut in. "We need to form a plan and develop whatever weapons we can to destroy the Horcruxes first. That way, we're prepared for them when we find them."

"Sev's right, James," said Lily. In her mind, taking on a basilisk that could kill with one look was somewhat more terrifying than breaking into the Malfoys' place. "But I think, for this, we need more than just the three of us."

Severus seemed hesitant, but soon nodded. "If one of us gets petrified, we need people to take over straight away. Lily, I want you to be on hand to administer the draught if anyone does get petrified. Who else do you trust to go down there?"

"Remus, Sirius and Peter, of course," said James.

Lily reacted before she had time to think. "Not Peter!"

"Why not? Lily, he's one of my best friends. I'm not bringing the others and leaving him out," replied James, clearly taken aback.

Lily wanted to kick herself while also being adamant that a future spy for Voldemort was not welcome among their party. "Peter is lovely. But be real, James, he lacks your courage. Ask yourself, truly, how would Peter fare against a basilisk knowing it could kill with just one look?"

Peter hesitated. A fatal moment of hesitation in which he subconsciously admitted the truth of what she had said. But Lily's triumph was short lived. "I cannot exclude Peter."

"Look, you know that Girls' Toilet haunted by the kid who cries all the time?" Severus said, seemingly completely changing the subject.

Lily was mystified. "You mean, Moaning Myrtle?"

"Yes, that's her. Those toilets were built over the entrance to the Chamber of Secrets. Look, that's how Myrtle was killed: by the basilisk the last time it was opened back in the fifties. Anyway, that's going to be our way in too, so we'll need people standing guard in there. Peter can do that if you don't want him getting under our feet in the Chamber itself?"

That was not Lily's concern but James was happy. "Perfect, Snape."

Lily backed down, turning her attention to her potion. Adding more mandrake roots, she stirred clockwise and then counter-clockwise, trying to reassure herself that Peter Pettigrew couldn't possibly do any damage if he was just standing guard. Meanwhile, James was still restless. I levitated a cauldron over to the bench and set up beside Lily.

"Look, I'm no potioneer," he said. "But I need to do something. So, I'll do my best, all right."

Reminding herself that it was she who got these two to finally talk, Lily allowed herself a smile. However, no matter how much she focused on her own potion, her mind wandered back to Horcruxes. The diary was one. The others could be anywhere. In her mind's eye, these dark and deadly items screamed. Souls trapped and anguished, tormented in their bonds of leather and steel. It sounded worse than hell and it made her skin crawl.

When it came to let their potions stew, Severus hid them in a disused cupboard she had never seen before. It was built into the back of the store room, an ante-chamber clearly not many people knew about. "Dumbledore said we need to go home with everyone else, but we can come back and check on the potion as needed before we finally do this thing," said Severus, sealing the door magically. Slughorn would be gone before dawn, so it wasn't like he would find their illicit brew.

Eventually, James left them with the promise of a meeting on the train during their imminent journey home. And finally, Lily had Severus on his own again. The two of them sat upon a table with their faces turned to the light, the windows open again to let in the broad afternoon sun. They sat so close their sides touched and she let her head rest of his shoulder. "No matter how we go about this, there will come a reckoning, won't there?"

It felt impossible on a day like this. A hot day during the country's hottest summer, when everywhere she looked people laughed and waded in the usually freezing lake. She felt Severus lean his own head against hers. "Yes," he said, voice as soft of satin. "Yes, there's a reckoning coming. And we need to be ready for it when does."

They were already at war anyway. A war that, until she learned about Horcruxes, had felt so distant, so very far away. "We'll face it together," she said. And she meant it.

Thanks again for reading; reviews would be lovely, if you have a minute.