Lupin felt a familiar warmth well up without warning from the depths of his memory.
It was a complex scent mingling cheap honey sweets after a prank, old parchment in the Restricted Section, and applewood burning in the Gryffindor Common Room fireplace.
His body still stood in this cold, damp mine passage.
But his soul had returned to that noisy dormitory.
James was gesticulating wildly as he explained Quidditch tactics, his sweeping arms almost reaching the ceiling.
Beside him, Sirius had enchanted his quill to tap-dance on the desk, its clicks keeping time with James's impassioned voice.
And Peter...
Peter was watching them with pure, unadulterated adoration.
In his hand, he still clutched a Cauldron Cake squeezed out of shape by the warmth of his palm.
Lupin's thoughts sank further, into that freezing little shack.
The Shrieking Shack.
On the Night of the Full Moon.
There was no fear in the air there.
Only three illegal Animagi stubbornly crowding around him.
James took the form of a stag, agile and elegant.
He drove away imagined dangers with his hard antlers, and dispelled the darkness in Lupin's heart with those gentle eyes.
Sirius became a huge black dog, always baring his teeth in a goofy grin.
He would nuzzle Lupin's hand with his wet nose, his warm body and silent companionship the only comfort in Lupin's chaotic world after transforming.
Even timid Peter turned into a tiny rat.
He scurried around Lupin, squeaking, trying in his own insignificant way to share that soul-rending pain.
Those full-moon nights had once been the darkest curse in his life.
Yet their presence had turned them into a strange, secret ritual mingling pain and warmth.
They had even given him a name.
Moony.
A teasing nickname.
Yet full of the clumsy tenderness unique to boys.