Wolf and Dementor
There are a few situations in one's life when your whole time on this plane of existence flashes before your eyes. For Remus Lupin, it was every single time he closed his eyes. He could remember the tearing of flesh, as rough teeth tore through his shoulder and sharp claws scratched at his face. He recalled vividly the scent of raw power, pure anger as it hulked over him in a wolf-like shape. He could accurately describe how it felt when Fenrir Greyback stole his life away from him.
It revisits him every single time he encounters a dementor. "Vile Creatures," he could remember the groundskeeper telling him years ago when he went to Hogwarts. The kindly giant would look down upon his studious friend with a hint of a smile. "Not a chance in hell I would want to meet with one o' them again,"he'd continued. "Jest you 'member, Remus, the Patronus Charm is what you need."
They were always the words Remus heard before the childhood screams met his ears. The Patronus Charm. Of course, it wasn't so easy, what with needing a memory. Not to mention a happy one when the horrors of your past came to you. But it was in this instance that the happiest memory Remus had ever had that banished the wraith.
He oldest friend's son. Sat in happiness, talking with his friends. His own version of Remus, albeit in the form of a short, bushy-haired girl, and his own red-headed Sirius-Peter hybrid, as Remus hoped him to be. What with Sirius turning out…
No, Remus thought. Don't think about that. By that time the dementor had arrived, and Remus saw the only link to his former life fall to the floor in fitful terror, the dementor's veil of darkness shrouding the compartment. He whipped out his wand, imagining seeing Harry Potter alive and well again, smiling in his class.
"None of us are hiding Sirius Black under our cloaks. Go."
The dementor did not react, only to draw in a deep breath, the air rattling like a child with a toy. But there was no joy, no happiness to be found in the sound. Remus held the thought more clearly in his head, trying to ignore the essence of Greyback that filled him with dread.
"Expecto Patronum," he murmured.
A silvery tiger burst forth from the tip of his wand, charging down the dementor that gripped on to the clammy hold it had over the compartment. It quickly released and turned, charging away. Remus gave a grim smile, before turning back to Harry Potter, his best friend's son.
To the inspiration of many dementor's banes.