Author's note: Yes, the first few paragraphs are entirely taken from the book, to give context to the story and to flow smoothly, but eventually it gets to the original part.
"I want you to take this," Sirius said quietly, putting a badly wrapped package into Harry's hands.
"What is it?" he asked.
"A way of letting me know if Snape's giving you a hard time."
Harry started to unwrap it but Sirius stopped him.
"No, don't open it in here!" said Sirius looking warily at Mrs Weasley, who was trying to persuade Fred and George to wear hand-knitted mittens.
"I doubt Molly would approve - but I want you to use it if you need me, all right?"
"OK," said Harry, stowing the package away in the inside pocket of his jacket, but he knew he would never use whatever it was.
"Let's go, then," said Sirius, clapping Harry on the shoulder and smiling grimly, and before Harry could say something else, they were headed upstairs, stopping before the heavily changed and bolted front door, surrounded by Weasleys.
"Goodbye, Harry, take care," said Mrs Weasley, hugging him.
"See you, Harry, and keep an eye out for snake for me!" said Mr Weasley genially, shaking his hand.
"Right - yeah," said Harry distractedly; it was his last chance to tell Sirius to be careful; he turned, looked into his godfather's face and opened his mouth to speak, but before he could do so Sirius was giving him a brief, one -armed hug, and saying gruffly, "Look after yourself, Harry." Next moment, Harry found himself being shunted out into the icy winter air.
Behind him the door closed shut. On the inside the chains drew back up, sealing the door. Sirius was left with Mr and Mrs Weasley and Kreacher.
"Right then," said Sirius, "I suppose you two will be off soon then."
"After dinner, I think." replied Mrs Weasley.
"Alright,"
Sirius bolted up the stairs, slowing down slightly when he reached his mother's portrait. He ran to his room and opened his sock drawer and found a small mirror. Sirius had just given a matching mirror to Harry. Sirius started to recall his school days with James. The two had used these mirrors to communicate when they couldn't be around each other, whether it be holidays or in separate detentions. Sirius figured he would give James' old mirror to Harry so they could communicate without worry of someone intercepting owls or Harry getting into more trouble. He smiled at the fact that soon he could talk to Harry, face to face, regularly for once.
The mirror reflected Sirius' own face, then quickly the blackness of inside Harry's jacket and muffled talking, and back to Sirius.
"Scoundrels, mudbloods and blood traitors…" Kreacher mumbled. Sirius quickly slid his mirror into his pocket and got up. He was giddy. He was hoping to talk to Harry tonight and explain more about the mirror. For now he could only wait, for he doubted Harry would open it while he was walking, nor on the train, for it would be too risky with people walking in the halls, or until after dinner on the Hogwarts express. So he guessed it would be a dessert treat, but eventually Harry would open the parcel.
He slipped out of his room and went back down to the kitchen. Sitting and reading the paper, waiting patiently.
After dinner, Molly and Arthur gathered their things and were off, bidding Sirius farewell, and after around of hugs they were out the door.
Sirius then took out his mirror and looked into it.
Only darkness.
Maybe he was still eating dinner? Or maybe just returning to his dormitory.
Sirius returned upstairs and performed his toiletries, keeping the mirror in view at all times just in case Harry opened it.
Nothing.
Sirius climbed into his bed and listened to the silence, and the occasional grunt from Kreacher floating around the house. He leaned the mirror up on his bedside table and laid back.
Eventually Kreacher went to bed and silence filled the house, and Sirius was still staring at the ceiling, listening for Harry's voice in the mirror.
All night, nothing came from the mirror.
Maybe he was just tired from the journey. Definitely tomorrow. Sirius thought.
He woke up the next day and checked his mirror. It turned to the dark of Harry's trunk. He couldn't hear anything from the other side, so he put the mirror back down. He decided to get dressed and go down stairs. He placed the mirror on the kitchen table and fashioned himself some eggs.
At around noon Mad Eye showed up with the Prophet, Sirius quickly slipped the mirror into his pocket. He stayed for small lunch and chatted with Sirius for a bit, but ultimately left before the hour. Sirius took the mirror out again and place it flat on the table. He sat listening to Kreacher roam, doubting he was doing any real work. He read the Prophet two times through and found nothing of interest. He gave the mirror one more look, but there was nothing, just the reflection of the kitchen ceiling.
The day passed by without the mirror changing. Maybe just a rough first day back, lots of homework to get through.
The third day passed just the same, when he looked into the mirror it either only showed the darkness of Harry's trunk or Sirius' reflection. An Order member showed up to deliver small news and a paper, and some muggle magazine he had requested.
The fourth day, just the same. Then the fifth and the sixth. The seventh passed the slowest. It was the weekend, surely Harry would open the package then. He sat in the kitchen waiting to no avail.
The weeks passed, and soon it was February and he hadn't heard a word from Harry. Occasionally he would look into the mirror and hear muffled talking, to which Sirius would try to catch their attention by calling Harry or Ron's name, but nothing ever came of it.
Once a week Mrs Weasley would come to visit. Kreacher would scowl as she entered, as always. They would have tea, she caught Sirius up on any major news of the Order, and brought groceries for him.
After a while Sirius started to seem less and less interested of their chats.
"Is everything alright, dear?" She asked one afternoon.
"Hmm? Oh, yes," Sirius would reply. "Just, being shut up here alone with Kreacher gets to you." And that's all he would say.
Soon it was March, but Sirius still kept the mirror with him at all times, just in case. When he felt bored he would stare into it, occasionally flicking back to the bottom of Harry's trunk.
What made the experience worse was that he knew the mirror was working. He could hear their voices, but they never opened the mirror. He felt more neglected now than ever. For once he has a way to contact Harry, but Harry has been ignorant the whole time.
By April Sirius had given up on the mirror. He kept it on his bedside table but he never picked it up. Some days he refused to get out of bed, but when he did he never got dressed. It was lonely in the house of his parents. Especially without Harry to cheer him up. Despite having giving up hope that Harry would ever open the mirror, he still fell asleep looking at the mirror every night.
June. Sirius lay in bed. Mrs Weasley dropped off the groceries and left lunch outside Sirius' door. She left without knocking or calling for him.
Then he started to hear Harry's voice. He must be going mad, Harry wouldn't pick up the mirror now, after not using all this time. He jumped to pick the mirror from his bedside. His own reflection stared back at him.
He started to cry, and Kreacher started laughing in the kitchen.