Something wasn't right.

"Peter!? Peter, open up!"

No, Sirius Black thought as he knocked on his friend's door for the third time, something definitely isn't right.

"Peter? Peter, I'm coming in! Alohomora!"

Sirius only narrowly avoided using a blasting curse to throw the door off its hinges, so panicked was he of what he might find in Peter's flat.

Sirius had been planning on going deep into hiding today, to play the part of someone with something to hide and to continue to let Voldemort's forces believe that he was Lily and James' Secret Keeper. That had been something that James was adamant on when he had told his best friend his plan to keep the heat off Peter and make sure the other wasn't targeted. Sirius had protested at first, believing that to be a waste of resources as he wasn't actually the Secret Keeper, so it wouldn't matter if he was caught and they would just be denying the Order a much-needed soldier. Lily had been the one to point out that if he didn't go into hiding himself then it would be far more likely that the Death Eaters would figure out the ruse, and they might decide to target others, like Peter, McGonagall or Frank and Alice, and although he knew that Lily was just trying to convince him to protect himself, he had to agree with her logic.

After, that is, he had endured the twenty-minute vehement rant that James had subjected him to for referring to himself as a 'resource'.

"Peter are you here!?" Sirius could barely hear his own urgent calls over the panicked beating of his heart as he searched the flat for his absent friend.

Sirius' plan had involved holing up in one of his Uncle Alphard's properties in Oxford for a few days, just to ensure that he was nearby in case the misdirection didn't work, and someone figured out that Sirius wasn't the Secret Keeper, or they decided to target the other Order members anyway. He would check on Peter after the third day, just to make sure the other was alright, before moving to London with a fake identity. After that (and unknown to James, since Sirius knew that he would disapprove greatly) he was planning on joining in the war efforts from the city and seeing how many Death Eaters he would be able to take out from there.

"Peter! Where are you!?"

Only James, Lily and Peter were aware of his intentions (minus the last part), and he had made them promise not to tell anyone. Due to the fact that they were aware of there being a traitor in the Order, it wasn't as hard as he had thought it would be. They hadn't even argued when he told them not to tell Remus, considering not only how difficult it would be to even tell him in the first place since he was constantly infiltrating Dark werewolf packs as a spy and it wasn't exactly something they could inform him of over an owl, but also because it would be a lot more dangerous for the other Marauder to know and it would be safer for the spy if he had one less secret to carry and potentially be tortured for. In fact, the only person that they had fought him on leaving out of the plan was Dumbledore.

("You don't trust Dumbledore!?" Lily gave her husband a look at his incredulous outburst, but by her silence Sirius knew that she agreed with him.

He pressed his fingers to his eyes tiredly, "It's not that I don't trust him… I just don't think it's a good idea to let too many people know. Secrets shared too many times have a way of getting out."

"Yeah but come on. Dumbledore: Leader of the Light, the one person Voldemort fears."

"Exactly. Dumbledore is a political genius, a war hero and a respected and powerful figure in the wizarding world. Voldemort doesn't just fear him. He respects him. Because Dumbledore is everything that he wanted to be; he's almost god-like in our world. And," Sirius sighed, "that's why he's so dangerous. He's an absolute master of manipulation. He sees the battle on a level no one else can; he gets a shrewd idea of what the enemy is up to and he can predict their next five moves and at least six motives. He manoeuvres players in times of peace, so they are positioned to the greatest advantage during times of war. He can see the value in people no one else can; he sees the potential they have and what they can become so he gives them the fair opportunity they deserve, and in doing so he gains their trust, loyalty and respect." Sirius paused what had become an impassioned speech, thinking about Remus, before heaving a sigh and continuing in a softer voice.

"Dumbledore is a great man who does great things - and even good things, when he can – but he knows exactly what he is doing with every decision he makes. His number one priority is the 'greater good', and I'm not denying his success in that, but I don't trust him to always look after the people on the smaller scale. He'll do what he can, but he won't ever risk the future he's trying to create for them."

Sirius waited while a shocked Lily and James absorbed what he had said and absently wondered if they were surprised by his insight or surprised by his insight. A cry from Harry a few moments later broke everyone from their thoughts and Lily immediately moved to comfort the infant, bringing him over to the two men while gently bumping him up and down until he settled. Sirius watched James watch Lily who watched Harry who was reaching for a loose lock of Lily's hair – no doubt to once again try and suck on it – and he knew that the two parents were thinking about what his words could mean for their son.

"Alright."

Sirius blinked as Lily unexpectedly spoke, her eyes still on Harry.

"Sorry?"

"We don't tell Dumbledore," now she looked up as she explained, and Sirius noted that her brilliant green eyes were brighter than usual. "We don't tell anyone. Not unless we have to."

Still surprised, Sirius didn't say anything until James huffed a laugh. "Yeah, but Pads, we've got to talk more about what you think Dumbledore's up to at some point. I had no idea you were that insightful," he teased at the end.

Sirius gave his signature smirk, casting off the part of him that had been cultured by his years of living with the Blacks in exchange for the Marauder within, "Well, one of us has to be. We can't all afford to be idiots."

He continued to smirk as his best friend, who was another brother to him, gave a bark of laughter and his wife, who was like the sister he'd never had, softly chuckled while their son, who was his godson, nephew and pup all in one, giggled at the sounds of his parents' joy, before James, unable to let that go unanswered, began a long, banter-filled debate on who the bigger idiot was that lasted well into the morning.)

"Peter?" Sirius called one last time, his voice softer as it finally sunk in that the other was not there to answer.

Something isn't right, Sirius thought again, and he tried to force himself to calm down and look around the flat deliberately. It was then that he noticed it, and, all of a sudden, he began see what he and everyone else had missed for months.

Something is very, very wrong.

It was on the morning of the 31st of October - the morning of the third day of his plan - that Sirius had begun to feel uneasy. They had cast the Fidelius charm as soon as they could, less than a week prior, and Sirius had spent the few days he'd had before hiding out at one of his uncle's houses tying up any loose ends he needed to and preparing for his move to London as stealthily as possible. Sirius hadn't been sure where these feelings of tenseness had come from, as he hadn't anticipated feeling them until he was about to leave for the city.

Unnerved, and with too much experience as a soldier in a civil war, a Hit Wizard under Alastor Moody, a prankster and Marauder at Hogwarts, and a Gryffindor in a Slytherin household, he had been unable to dismiss his instincts as paranoia. That had led to him sweeping his own apartment for any enchantments on the off chance that his location had been found and booby-trapped or bugged, mentally running through every interaction he'd had in the previous week to see if he could remember anything off about any of them and re-evaluating his plan to make sure he hadn't missed anything.

By the time the blue sky outside had begun to turn pink and orange he still hadn't found anything to account for his unease, but, if anything, that had only made him feel more nervous. Glancing agitatedly out a window at the darkening sky, Sirius had decided to move his schedule forward and check first on Peter, then James and Lily, early. He hadn't planned on leaving the house initially until it was well into he night and he had the cover of darkness, but with his instincts flaring the way they were, Sirius had decided that the early evening of quarter-to-five in October would have to do.

For once cursing the precaution they had taken of setting up anti-apparition wards at both his friends' locations, Sirius had been grateful that he hadn't yet done anything to his beloved – yet easily recognisable – motorcycle. Due to its uniqueness, Sirius had known that he wouldn't be able to take it to London, as it would be a risk to his cover, but he had been loath to get rid of it and had decided to deal with it last, just before he left for the final time.

Thankful for that decision, Sirius had soon set off into the sky, travelling quickly yet cautiously to Wormtail's flat and hoping to the Founders, Merlin, God, St Nicholas, Led Zeppelin and any other deity he could think of – be they magical or muggle – that everything was alright.

This couldn't be right. Not Peter. In fact, there were probably hundreds of other explanations for why Peter's flat was empty of both Peter and any signs of a struggle. He could be making his own last-minute preparations before going into hiding, or maybe something had come up and he was doing something with the Order, after all, they didn't know of the switch in Secret Keepers, so they wouldn't realise that he should be in hiding in the first place.

If it were something that simple he would have left me a note, a traitorous voice whispered in his mind, forcing him to consider a darker option (but one that was still preferable to the other possible conclusion he had drawn – that one he wouldn't, couldn't, even consider of his friend just yet, not until he had exhausted all other options).

Maybe the Death Eaters had found out about the switch or had just decided to go after an Order member and known friend of Lily and James' in the hopes that he would be able to give them their location. They could have found out where Peter lived in any number of ways and set up an ambush to catch him unawares. That was feasible, since, as much as he loved his friend, Sirius knew that Peter didn't possess the instinct for danger and almost paranoid spatial awareness that he and Remus both had, nor James' sheer dumb luck, as Minnie would say. Peter might have been captured before he'd even known it, and that was why the flat didn't look out of the ordinary.

But… Perhaps he hadn't. Perhaps Peter had left his flat of his own free will. Perhaps… A large part of Sirius hated himself for even considering this, but he couldn't deny that it was a possibility.

Perhaps Peter was the traitor.

As soon as he'd allowed himself to truly consider the thought, Sirius knew that he was right. Call it instinct, or intuition, but as soon as the thought took hold he began making connections between many a suspicious circumstance or death in the Order that they'd never been able to account for and his dear friend and fellow Marauder. Caradoc. The failed ambush on Moody. Benjy. Marlene and her family. Several failed missions that Wormtail had been privy to.

Sirius allowed himself a moment to mourn for the friend he'd thought he'd had before a harrowing realisation struck him like thunder and his muscles seized for a moment in his horror.

Prongs, Lils and little Harry.