The Haunting of Hanover-Square by StudyInScarlett (JSAMN, Johnsquared)

╰┈• When John Segundus was a boy, the millpond in the village had held a certain fascination for him. Over the spring and summer, he would walk down and watch avidly as the frogspawn grew into sludgy, wriggling blots of tadpoles and long-tailed froglets - then finally frogs, which poked their wet, shining heads out of the water on warm summer days and crawled cautiously onto the sun-dappled banks.

But the winter he remembers best, for that was when the pond often froze over entirely. He and Simon would slip out unnoticed, then, Mr Segundus having been too prone to sickness to be allowed out in the cold. Perhaps it was inadvisable, but then no harm ever came of it.
The ice was thick. Several times, Simon had stood upon it (simply, Mr Segundus suspects, to laugh at his younger self's sudden yelp of alarm). His mind returns every so often to those days - to him bundled up in a half-dozen layers, crouched by the banks as Simon idly throws pebbles onto the surface of the frozen pond. To him watching the contents of it suspended indefinitely, wondering if its inhabitants had so much as noticed the slowing of their lives.

No longer a youth, he has become aware that this is not how the freezing works, but the child's naïve flight of fancy lingers yet - he has often thought that it might be a fine thing to preserve a moment so - infinite, lingering, bound not by the transient constraints of time. Merely the serene silence of the ice and a boy tossing pebbles onto the pond somewhere. 
And here, decades later, are his and Childermass' hands hanging between them, linking them together, one moment out of the many moments he might like to freeze in time like a millpond in winter.