It was the one thing that was supposed to console him that cut Locke the deepest. They all told him the same story: right before she'd died (cut down by shrapnel, they said, and finally eaten away by an infection beyond the skill of their rustic doctor) Rachel's memory had come back to her. Her last request before the delirium took her was to tell Locke that she loved him; her last words, wracked with fever, had been his name.
To the friends he'd left behind in Kohlingen, this was a comforting thing. It was the triumph of Love with a capitol L. Even if it was at the last possible moment, Rachel had remembered him, called back all of their shared memories she'd lost. She had died in love with him again, and all was put tragically to rights.
This is what everyone else thought of her dying words. Locke only heard a cry for help that had gone unanswered. Try as he might, he could not be happy she had remembered him at her death — it only meant that she knew, as she lay coughing blood onto the blasted soil, that he was supposed to be there to protect her. And when she needed it most, he wasn't. She'd loved him at the end, yes, and forgiven him too, it seems — but she still died knowing that the one she loved had failed her.
That, Locke always thought, was what had driven him mad.
He had to be mad. Sane people moved on, found new lovers, left flowers on gravestones and remembered the dead without guilt or aching regret. They most certainly do not cut under-the-table deals with the undertaker who happens to be an amateur chemist (or perhaps 'alchemist' would be a better term) to have their deceased lovers held in suspended animation in some vain, outrageous hope of revival.
Before Locke had returned home to find Rachel dead, he'd heard the rumors of the Empire's witch, who could summon fire with a word and heal wounds with a touch. He'd heard of the machines which devastated opposing armies, powered by some unheard-of force. And everywhere, one word was whispered again, in earnest awe and fear: magic.
If you could call her, I bet she'd come back! That had been the undertaker's flippant reply to Locke's muttered wish that everything would be undone. If you could call her... But that was ridiculous. No one could cheat death.
But what was magic if not cheating the laws of nature? If the Empire really did have magic, or something like it, then there was a hope — a fool's hope, a madman's hope — that he could still save Rachel. And if it was anywhere, it lay within the uncaring machine that was the Empire.
He'd left Kohlingen again, not in despair but in resolve. Subterfuge came easy to him, and eventually he'd broken into enough Imperial laboratories and treasuries to warrant the attention of the resistance. He'd become the Returners' master saboteur and spy, and informer to the King of Figaro himself. And through it all, he made sure that not a soul could say that Locke Cole had failed them.
Every six months he went back to Kohlingen, and Rachel. He sat at the foot of her bed and watched her not breathing — never daring even the slightest touch, because he knew she'd feel cold and still, so jarringly unlike the warm and quick-limbed girl she'd been. The strange herbs of the undertaker had rendered her immune to the ravages that time wrought on the dead, but Locke could not make himself imagine, even for a moment, that she was merely sleeping. No amount of chemistry or herbalism could hide the unnatural stillness, or the fact that his own breathing was the only sound echoing off the cold basement walls. He brought two bouquets every time he came to town — one for the graveyard, and another for her resting place in the undertaker's basement. Each time he came back the flowers on the grave were long since gone, but the undertaker perversely employed his alchemy on the bouquets in the basement so they accumulated over the years. He claims he's saving them up for Locke and Rachel's wedding...rather a cruel joke, really.
There are ten bouquets in the basement now.