For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horse-shoe nail.
~ Fourteenth-Century Proverb
Case-study for historical military logistics
Presented as an illustration of the "butterfly effect" and in chaos theory
Allegorically related to the Camel's nose metaphor

They sat, side-by-side, arms nearly touching, in a heavy silence. Acutely aware of the others' presence, the air between them sank with the weight of the tension. His fingers dug into the flesh above his knees as he reigned in the shudders that threatened to wrack his body and bit back the questions that burned in his throat. Her chest stung from the dry tears that sat in her throat, acidic and abrasive, and her lips twitched as she fought the urge to throw herself into his arms. Once upon a time sleepless nights had ended like that, his hands on her hair as he whispered nonsensical words of comfort without ever asking why. Her mind blurred them together now – the battered man who'd loved the little girl she had been and the glass boy who sat beside the woman she had become. Scars superimposed on fragility and the face it presented her proved grotesque at best.

She could feel her tongue in her throat and gasped at how big it felt, how it suddenly closed her throat and fogged her breath. And her vision blurred – running and melting over her cheeks as she heard his soft question. Even his eternal patience had finally run out. 'Are you okay?'

'No.' the sound clawed past her tongue, low and throaty, and she climbed into his arms. He wasn't even the right size – her mind screamed that this wasn't her Sirius and her body thrummed with the desperation for him to feel like her Sirius – and the lean, sinewy form that held her tightly did not exist. Never would exist. Maybe. And that was her fault. She'd done even better than Bellatrix Lestrange. His cousin had killed him; his one-time saviour had destroyed his existence.

It never occurred to her to think that maybe it was for the best that his existence, as it had been, had been destroyed. All she could think, a morbid mantra that pounded itself into her skull so fiercely she could feel it imprint itself on her brain, was her fault. It was all her fault.

A/N - A thousand thanks to all the people who've read the story thus far! A hundred thousand thanks to all of you who reviewed or added this story to your alerts and/or favourites lists!

I know this chapter was super short, but it's establishing a crucial point for their relationship as well as setting up just how rocky a foundation it's based upon. I hoped you enjoyed it and, as always, reviews are very much loved... :)