Here's the blurb for the original novella when it was first published as a standalone:
It isn’t business as usual for Maelwine when a new family moves into Grave’s End House. With the old, great house standing untenanted for quite some time, being a house shade attached to it has turned the hours dull for Maelwine. He has no family to entertain him, no variations in his daily duty, which involves the rousing of shadows in every room when the sun goes down.From Chapter 9:
Things change when the Villar family arrive, however, and Maelwine is finally happily caught up in the comings and goings at Grave’s End. That is, until he notices Royden Villar, a young boy with a secret that depresses his spirits and touches Maelwine in surprising and alarming ways. The more Maelwine studies Royden’s behavior, the more he glimpses the other boy’s heart, and, suddenly, new paths reveal themselves to Maelwine -- paths that are as muddy as they are dangerous.
As a house shade, Maelwine is immortal and enjoys certain benefits that can only come with immortality. Not once has he questioned his situation. It is, after all, as Nature has always intended. But with Royden’s arrival, Maelwine’s forced to face difficult answers to unsettling questions about the nature of his existence.
He’s only a house shade, after all, and nothing more. He doesn’t have a heart, doesn’t feel loneliness in the shadows of his world. Things should be easy, but Royden Villar has set certain wheels in motion, and there’s simply no turning back.
Three more nights passed. Three more nights spent in an ever growing sense of deep isolation and loneliness to Maelwine. While it was true he’d managed to stick to his resolution of maintaining objective distance from Royden and the rest of the Villars, the determination had grown shakier by the day—or night, for that matter. On each succeeding evening, Maelwine found it increasingly more difficult to avoid pausing at Royden’s mirror if only to catch a glimpse of the other boy. Maelwine had at first thought he’d be satisfied with nothing more than a second or two of seeing Royden Villar reading or resting on the bed; he’d been quick to realize, however, that glimpses were simply not enough.
“I wish we could talk. I wish they’d let me,” he’d say over and over as he’d lay himself down on the floor, the weight of sleep gradually pressing down on him. Those were also the last words he’d say before finally succumbing to the darkness.
Christmas arrived, and Maelwine made sure to finish his work quickly, taking care to avoid thinking about Royden and how the boy was holding up. As was expected, Grave’s End was a whirl of activity, sound, and light. And while in the past, Maelwine was able to put up with the hubbub, this time he fled the scene, throwing his cloak around him and running off into the night and the lightly falling snow.
He didn’t visit any of the elementals, however. He’d decided early on he needed to experiment that night and see if he could cross paths with other house shades somewhere in the countryside.
“I’m sure they come out and have a talk with the elementals like me,” he’d said, and without giving his scheme another thought—otherwise he’d surely lose his nerve and change his mind—he’d scampered off, his cloak flapping wildly behind him.
He chose a random direction and stopped near the decaying ruins of a cottage about two miles from Grave’s End. There he paced and waited. Sometimes he’d amuse himself with a quick exploration of the ruins, which didn’t yield much, but he did wonder what happened to house shades whose structures burned down like this cottage. Would they be brought back to the queen’s kingdom? Would they be reassigned new houses to watch over? Or would they simply disappear with their ruined houses, dying the way mortals died?
Maelwine had never even thought along these lines, and his confusion about his existence as a house shade seemed to double. Why was he even wondering about these things when they’d never even crossed his mind till then?
He took a deep breath as he stood in the midst of blackened stone and rotting timber. “No one’s going to come,” he muttered, gazing around him. “I don’t know why I even bothered.”
And he was right. No other house shade appeared even for a moment. Not one came within his line of vision anywhere. He could only assume house shades either never abandoned their posts for whatever reason or they were invisible to each other—an extension of their isolation from the rest of their peers. Maelwine didn’t know how long he waited, but eventually gave up and retraced his steps back to Grave’s End.
The great house was lit up, its candlelit interiors stark against the darkness, the falling snow working like a delicate curtain that shielded the house against the rest of the countryside.
As Maelwine approached, he realized there were voices raised in song somewhere outside the house, and he stopped in his tracks to listen. Yes, he thought, there sounded like a group of people singing together, and he recognized the song currently filling the night air.
“It’s one of those Christmas songs mortals are fond of,” he said.
What was happening, though? His earlier disappointment gone, curiosity now moved Maelwine’s feet in the direction of the front door. He picked his way past bald trees and shrubbery littering Grave’s End’s rear and sides, eventually stopping just shy of the final corner of the house. He caught sight of a few people standing outside, facing the front door together, all bundled up against the chill, their faces glowing as they sang with so much energy and spirit in celebration of the season.
Since Maelwine stood off to the side and against the broken silhouettes of trees, he couldn’t see what was happening at the front door. It was likely the door was open, judging from the soft light that poured out into the night, welcoming the singers with warmth and cheer.
Maelwine listened in growing wonder. He’d never seen anything like this before, and he’d been through countless Christmases. Was this a new tradition? He held his breath as he listened to both familiar and unfamiliar songs, amazed at the harmony of mortal voices and wondering how the singers managed such a glorious chorus.
He glanced to his right without thinking, as his mind was utterly lost in the music, and didn’t recognize the pale and startled face staring out at him for what it was. At least not right away.
Royden Villar stood behind the window of the room directly across from where Maelwine was. The two boys looked at each other in varying degrees of shock. It was only then when Maelwine realized he’d not only stepped out of the safety of the trees’ shadows because he’d been so enthralled by the singers, but he’d stopped directly under the moonlight and had thrown his hood back and exposed his head in order to listen to the music more clearly.
It took a while for Maelwine to gather his wits, but during that time, Royden managed to rally. He fumbled with the window latch and threw the casements open.
“Who are you?” Royden called out, the look of shock still there. “What are you?”
Maelwine stepped back, not once breaking eye contact with Royden.
“Wait! Wait! I want to talk to you!” Royden leaned out of the window. Shock had now been replaced by panic.
A few more steps back and it seemed Royden could still see him. Maelwine eventually realized his hood was still off his head. He couldn’t hide from the moon’s light with him standing outside and depending on the pitifully sparse shadows of trees for protection against discovery.
Royden, to Maelwine’s dismay, had also grown bold. The ridiculous boy was actually climbing over the window in order to get out.
Maelwine immediately pulled his hood over his head just as Royden jumped down. With a hissed curse, Maelwine turned and darted from the scene, his hands firmly keeping his hood over his head. He could hear Royden calling for him, but the boy’s frantic pleas were easily drowned out by the sound of Maelwine’s ragged breaths. He didn’t know if Royden was running after him, and he kept his pace high, almost sliding in the snow when he rounded the rear corner of the house in order to vanish into the deeper shadows.
He slipped under a door, found himself in the kitchen, and immediately hurried to the nearest mirror. Maelwine avoided Royden’s bedroom for the rest of the night, choosing the chilly, dark silence of his world somewhere in between mirrors. It was safer there, he’d told himself. He was exactly where he should be. Let the mortal world carry on beyond the mirrors. He was only a house shade, after all. Nothing more.