Her heartbeat thrums so loudly all other sounds fade away. She sits tense and anxious beneath the black hat, suddenly sure that there's been some grave misunderstanding, or that she'll soon awake from the unfathomably wonderful dream of the past months, but then…."Gryffindor!" And she breathes a long sigh of relief, eyes trained deliberately away from the rude boy she met on the train as she searches for Severus, giving her friend a little shrug as she takes a seat among her new housemates.

His heart pounds with excitement as he enters the first year Gryffindor dormitory. He and his new mate, Sirius, sprawl across adjacent beds, grinning at the quiet boy opposite them and the nervous one beside him who tripped during the Sorting. Finally, Sirius voices what they're all thinking: "Well, guess this is home for the next seven years, eh?"

Her heart leaps instinctively as the Bludger misses him by inches; the crowd gasps, but the young Chaser only flashes his characteristic smirk as he zooms by, unharmed. It's a dangerous game, she acknowledges. Though she doesn't really know the boy—and doesn't really like the little she does know about him—she reluctantly appreciates that it takes talent and some amount of nerve to race around on a broom like that.

He barely reacts when the large, heavy ball whips past mere inches from his left cheek. It's only as he spots that familiar flash of red hair—the one his eyes can't seem to help finding in crowds both big and small—that his heart lurches in his chest. Forcing his focus back to the game, he decides it is exceptionally lucky that his silly reactions to the redhead are noticeable only to him.

He's infuriating, she decides as she storms away; there's no other way to describe it. Inexplicably, however, her heart clenches with guilt as she replays some of the angry words she shouted in her fury.

"She's infuriating!" he grumbles to Sirius as the pair watch her hurry down the corridor. His heart is pumping with adrenaline fueled mostly by anger but also, he grudgingly admits to himself, that certain thrill only she can cause.

She knows her heart should feel broken, or swollen with rage, or overflowing with indignation. But instead, it only feels empty.

He feels his heart as a keen pain in his chest when he catches her crying in the library a few days after it happens. But a teenager's underdeveloped sense of empathy leaves him without a way to fix it. And so he spends nearly the entire summer trying to ignore the remorse that weighs so heavily on his mind.

She finds herself smiling whenever she hears his infectious laughter ring out across the common room. And when he flashes her that crooked grin in the hallway after Charms, her heart skips a beat. She's not sure why—she doesn't like him. She can't possibly like him. And yet…

Something's different. He can feel it in the rapid hammering of his heart every time their eyes meet across a room. Sirius says he's just being stupid; maybe he is. And yet…

Her heart is thumping so quickly she can't feel a separation between the beats. And still he leans closer, his lips halting a mere breath's width from hers.

His heart soars as she closes the distance between them, her lips warm and firm under his. He wraps her in his arms, resolving to never let her go.

Her heart stutters with nerves as she walks down the aisle, her mother's words echoing in her ears…You're both so young…But as she stands before him and sees the pure love shining in his eyes, all her doubts melt away.

He swears his heart actually stops when she appears in the double doors of the church. He can't stop staring at her as she approaches, and when she reaches him a wide smile splits his face. "I love you," he whispers, and she mouths the words in return.

Her heart feels as though it's been hollowed out of her chest. Go into hiding? It feels like giving up, as though they are accepting the inevitable horror that has been chasing them all summer.

His heart feels as though it's breaking when he catches sight of her frightened expression. Words fail him, however, and so he simply takes her hand and squeezes it, feeling the smallest sense of comfort when her eyes soften slightly at the gesture.

Her heart goes numb as he yells for her to run. Fear hits her so powerfully she remains frozen for several seconds in the doorway. But then her husband shouts Harry's name, and suddenly her heart beats with a determined strength. She knows she must protect her son at all costs.

He feels a tug at his heart as his wife and son flee the room. He knows he can offer little for their protection, and the thought pains him. But there is no fear in his heart as he faces down death, head up and eyes forward. There is only love.

Where three hearts once beat, there is now but one. This heartbeat is quick and strong—a sound of hope for the future. A heart that will one day save the world.

A/N: If it wasn't clear, that middle-ish one where Lily is talking about her heart feeling empty is referring to the events of SWM.

Happy Halloween, everyone!