A/N: This idea has literally been swimming around in my brain since 2006. It feels very cool to be able to get it out into the world! The inspiration is basically, that the very last thing that James does in his invisibility cloak MIRRORS the very first thing that Harry does when it's his turn. :)
Hope you enjoy!
James Potter, unable to sleep, swung his feet out of the bed and stood as quietly as he could. He gazed down affectionately at his beautiful wife, her hand hanging off the mattress as though she'd been rocking the cradle when she'd fallen asleep.
Harry, their perfect son, had just turned a year old, and he was usually a very good sleeper. James resisted the urge to pick up his baby just to cuddle him, and instead shoved his glasses on his face and snagged a cloak that was sitting on the bedside table.
He ran the material through his fingers, watching it waterfall as though made of liquid. This was one of James' most prized possessions, and he couldn't wait to pass it on to Harry, nor to hear all about the trouble his son would cause when it was his turn to go to Hogwarts. James started to grin, but reality hit him instead. They just had to make it through this… through tomorrow.
Tomorrow was the day that Dumbledore was going to cast the Fidelius Charm for his small family, sending them into hiding for as long as required. On Dumbledore's insistence, they were staying at Hogwarts tonight while the Order prepared and secured their home in Godric's Hollow. This time the following day, James would be decisively cooped up, and he wasn't even sure how long it would last.
Dumbledore had asked to borrow his precious cloak, claiming he wanted to examine it, but James was suspicious that the sudden desire was in no small part to remove the temptation from his hands, keeping him housebound. He honestly couldn't really blame Dumbledore. As much as James understood he wasn't safe, he didn't doubt that he would eventually begin to feel quite stir crazy.
Tonight though, he couldn't sleep and he had his cloak for one last midnight Hogwarts adventure. James grinned and flung the cloak over his shoulders, feeling invincible as it settled around his feet. He pulled the hood up and stepped quietly into the hall outside the visitors' lodging.
The castle was quiet, it being the summer holiday, but even so, James tried to keep his footsteps silent as he traced familiar paths and took shortcuts instinctively, walking he didn't even know where. He almost wished he had their old map, the one that Filch confiscated his seventh year. Maybe he'd sneak into the old squib's office and nick it back tonight. Sirius would be ecstatic. The thought made James grin.
He turned into a wide corridor and paused, taking a moment to figure where he was. Deciding he was somewhere on the fifth floor, he waltzed down the hall a bit then veered to a door on his right. This should be the Transfiguration classroom. Maybe he could leave a note for old McGonagall on the chalkboard. Or a few curse words, just for fun. Surely she'd blame it on Peeves.
When he opened the door, however, he stopped in his tracks, surprised by what he saw. The classroom was clearly unused, all the chairs and desks pushed to the back. Alone in the front was a free standing, full sized mirror in an ornate golden frame. He held his breath for a moment, as though waiting for something to happen, but the room remained silent and unmoving.
Reasoning that he must be a floor too high, James approached the artefact casually. It was always fun to look into a mirror while wearing his cloak, and not see a reflection. He'd just have a peek then hurry on to prank McGonagall.
He gasped aloud when he stood in front of it. Instead of being alone, he saw Lily standing next to him, her arms wrapped around his waist as she looked up at him, smiling. Her belly was round, positively popping with new life. Little Harry sat on his shoulders, a miniature version of himself, grinning and waving enthusiastically.
James whipped about, hands groping wildly at the empty air. His heart was hammering, unable to understand what he was seeing. He peered closer at the frame, trying to make sense of it, and noticed a string of gibberish he hadn't seen before. He squinted, taking a step, examining it for several minutes. Then it occurred to him: it being a mirror, perhaps he simply needed to read backwards.
I show not your face but your heart's desire.
The sentence settled on his heart, and this time when he looked at his reflection, the adrenaline wearing off, he fully understood what he was seeing. This was his family, safe and sound, having survived the war. This was his family, happy, together, thriving. This was his heart's truest desire.