This is based starting from the beginning of Prince Caspian, going off the assumption that fauns are immortal, and that Lucy and Tumnus were in a relationship before she and the other Pevensies vanished.
For the others, Narnia was like a dream, a magical place visited for a while, then left to return to the humdrum reality of England in the 1950s. But for Lucy, Narnia was the real place, and England only a humdrum interlude between going home. She’d lived in Narnia more than twice as long as she’d lived in England, it shaped her, informed her attitude, her actions. She lived and breathed Narnia; England was miserable and gray, and she was a *child* there. Peter, Edmund, and Susan were British schoolchildren dreaming of being kings and queens of Narnia; Lucy was a queen of Narnia having nightmares of being a small British schoolgirl.
The Pevensies stood on the beach for a moment, looking out across the channel that separated them from the mainland and taking in their situation. They were stranded. It was Edmund who first looked around, and frowned.
“Hold on, where’s Lucy?”
A frantic search ensued, but no amount of shouting, bush beating, or crisscrossing of the island produced their younger sister. They finally gave up, exhausted, just as the sun was beginning to set.
“Where on earth could she be?” Susan worried, fingering one of the wild apples they’d found without taking a bite, although they were all tired and thirsty.
“Perhaps she’s back in the station,” Edmund offered optimistically.
“Well, wherever she is, we won’t do her any good sitting here worrying about it and starving ourselves,” Peter sighed. “Come on, eat a few of those apples, then Ed and I will go get some firewood and we’ll camp out in that ruined courtyard.”
“Walls on three sides are better than none,” Edmund agreed, tossing his apple core into the brush and rising. “Let’s go.”
“Good luck, Lucy,” Susan whispered into the night, then sighed, got up and followed her brothers into the abandoned castle.
* * *
Six months earlier, Narnia Time
Lucy stumbled out of the silver mist and ringing horn blast that had swept her away, sideways and backwards from the rest of her siblings. Her foot caught in something on the ground, and she dropped to her knees.
Ah! Cold! She scrambled up again, rubbing her arms vigorously. The stuff that had caught her foot was snow- the ground was covered in it, as well as the trees and the entire landscape, as far as she could see. She raised her hands to blow into them, and stopped, staring.
The sleeves of her blazer, which had covered her entire arms only a few moments ago, now stretched to only just below her elbows. She looked down; a lot more leg was showing than there should have been. In fact, her entire outfit seemed to have been outgrown by about ten years.
I’m me again, she thought wonderingly, turning her hands over to examine them. Her fingers were long and slender, not the short, stubby eight-year-old things they’d been that morning. Thank Aslan, I’m *back*.
Lucy couldn’t understand how the others had adjusted so well when they’d returned; perhaps it was because they were older than Lucy, and closer to the size their adult bodies had been (would be, whatever), but they had seemed to have no trouble remembering how their younger bodies worked. Lucy had spent a miserable few weeks after their return from Narnia constantly misjudging the length of her arms, her stride, and the strength of her grip. Being seven years old again had been *hard*, and a year later she was still clumsier than she’d been before she’d grown up, and then shrunk down again. Not to mention being *treated* like a seven year old again, which was awful. She had to fight the urge to raise a haughty eyebrow at the older students at school when they tried to order her around- what was a ten year old *child* doing speaking to *her* that way? She was an adult, and a queen besides!- before she remembered that she *was* younger than them, after all.
She breathed out in huge relief; her breath steamed in the air in front of her, and she was reminded how very, very cold it was, especially in an outgrown school uniform.
Right. First, shelter. She started forward purposefully, and almost tripped over the figure that had been hidden a few feet in front of her by a hump in the snow. She blinked down at it, eyes huge. It was…
“Tumnus!”
He was unconscious, his lips were blue, his breath barely steamed in the air, and there was a bloody gash from his right shoulder to the bottom of his sternum. She dropped down next to him, the cold suddenly her least concern.
“Tumnus, by the lion, don’t die! Who did this to you?” She reached to check his pulse, frantic- he was cool to the touch, that was very bad, usually his body temperature was higher than hers- and found it, weak and thready but there, thank Aslan. “Damn, I wish I had my vial,” she murmured to herself, then looked up, checking her surroundings. Everything looked strange, at first, and she cursed again, quietly. Who knew how long it had been since she’d left? Tumnus didn’t look any older, but fauns were immortal anyway, so that didn’t help her much. Finally she recognized, there, that rock formation, with the streaks of marble just *so*… and that means…she turned back to Tumnus, checked quickly but thoroughly for any other injuries he might have (his collarbone was broken, which was going to make this painful, but at least he was unconscious and wouldn’t feel it, and it wouldn’t do any further damage), and hauled him up, draping his good arm over her shoulder and wrapping her other arm around his waist in a fireman’s carry. She blessed Aslan for restoring her to her adult self; she never could have done this as an eight year old, and even as a twenty year old it wasn’t easy, but luckily Tumnus was lightly built. They’d been almost exactly the same height, she remembered, half-hysterical with worry, when she’d left. Ruthlessly she shoved both worry and hysteria away and concentrated on supporting Tumnus and working out which way it was to his house. Northwest, if that rock was the rock she thought it was, and only a few hundred meters away. She oriented herself as best she could; checking the trees and the mountains just visible in the distance- the sun gave her next to no help, since the sky was a uniform overcast gray- and started out.
It seemed like hours later, although it had probably been more like fifteen or twenty minutes, when she finally spotted the familiar door of Tumnus’s cave. Her arms were burning with fatigue, as were her calves, but the rest of her was freezing, and her worry had made the short journey seem triple the distance. The door was off to the left a little; she’d been bearing a bit too far west, but she’d spotted it now, and picked up the pace as she slogged gratefully towards it in painfully tight patent-leather shoes and stockings that were already soaked through.
Thankfully, whoever had attacked Tumnus had left his cottage untouched, and there were even a few glowing embers still left in the fireplace. Lucy laid Tumnus gently down in front of the hearth and went back to latch the door, thankful that she’d remembered where the faun liked to hide the spare key. Her first order of business was to pull off her shoes and stockings so that she could move without limping; her feet uncurled and she breathed a short sigh of relief before she was busy again. She used some kindling to build up the last few embers of the fire and piled on logs until the whole thing was burning cheerfully. Tumnus’s body responded to the warmth by beginning to shiver violently, and Lucy sighed with relief. He was still strong enough to at least try to fight off hypothermia, that was good. The best way to warm him up would be a warm bath, but she doubted that he had a tub big enough to soak all of him at once. She remembered happy weeks spent here, in summer, in winter, bathing one at a time in a metal tub barely big enough to crouch in, laughing and splashing each other and…she shook the memory off, and concentrated on pumping water from the half-frozen pump to fill a cauldron. She needed to wash and stitch the gash, and she needed hot water to do that.
Focus on one thing at a time, she chided herself. Work quickly but don’t make mistakes. Prioritize. Her rules for dealing with battlefield injuries came back easily, very appropriate for the situation. The fact that she didn’t have her vial barely mattered; she’d only ever used it as a last resort, in any case, and had trained with the best doctors in Narnia so that she could deal with almost everything else. She blocked out the panicking part of her brain that was shouting, But it’s TUMNUS, and what if he DIES?? and simply dealt with what was in front of her. She finished filling the cauldron and hung it over the fire, rounded up clean cloths, needle, scissors, and plain linen thread (she had to hunt hard for the last, since Tumnus almost never sewed, but finally came up with half a spool in the back of a drawer in the bedroom), set them on the low table, and went back to check the water and Tumnus. The water was hot, and Tumnus felt warmer as well. He stirred slightly as she pressed her hand to his cheek, and her eyes blurred with sudden, unexpected tears.
I will *not* cry, he’s going to *live*, I have to *do* things right now, she thought, fiercely blinking them back and caressing Tumnus’s face gently. There would be time to break down later, but right now she still had to clean Tumnus up, stitch his wound, set his collarbone, and then get out of these ridiculous clothes. Despite her best efforts, however, two tears slipped by her eyelashes and splashed onto the faun’s face. He stirred again, blinked, and finally opened his eyes, squinting to focus in the firelight.
* * *
Tumnus awoke, dozy and feeling strangely separate from the dull throbbing across his chest and the sharper pain in his collarbone. He was cold, but his skin felt warm, as though he’d been cold all the way through and was starting to get warm again. He opened his eyes, wondering what had happened, and instantly knew. He was dead. This wasn’t what he’d expected death to feel like, but he was undoubtedly dead even so, because Lucy was there, crouched over him, looking concerned, exactly as he remembered her. He smiled.
“Lucy. I missed you.”
For some reason, her eyes suddenly brimmed with tears, and she bent down to press her face into the crook of his neck, taking big breaths that weren’t quite sobs. He instinctively tried to put his arms around her, and hissed as his collarbone scraped. Wait…dead people, Tumnus was sure, didn’t have broken collarbones. Still, he’d never been dead before…perhaps he should ask.
“Lucy,” he started gently. “Lu, don’t cry, come on.” A few more sobbing breaths and she got herself under control, just as he’d known she would; Lucy had never cried easily, she hated crying, and when she did have to cry, she stopped as soon as possible. She kept her face buried in his neck, though. “Lucy, am I dead?” This nearly got her started again. He felt her breathing hitch alarmingly, then she turned it into a shaky laugh and pulled back.
“No,” she answered thickly, rubbing away her tears with the heels of her hands, a familiar gesture that was so commonplace that it made Tumnus start to believe that maybe he *wasn’t* dead. Or dreaming. “You’re not. You almost died, though. What happened?”
Good question. His thoughts still felt thick and cotton-wooly; it was probably shock, the only reason he was taking Lucy’s sudden reappearance after twelve hundred years so well. Aslan. Twelve *hundred* years. Twelve hundred *years* since he’d last seen her. Aslan, she was beautiful.
“Tumnus?” she prompted, and he became aware that he’d been staring at her like at idiot. Right. She’d asked a question.
“I…Can I kiss you?” He needed to, suddenly, needed to feel warm lips and familiar flesh, to assure himself that she was really here. How could she be here? He resolved not to question it, in case she vanished as quickly as she’d appeared, leaving him for another twelve hundred years. She laughed, taken aback.
“Yes. Then, answer the question?”
“Mm,” he agreed, reaching up with his good arm to pull her down, ignoring the growing pain of the slash across his chest and his broken collarbone as he got warmer and more awake. This was far more important.
Lucy’s lips were warm and real, slightly chapped from the cold winter air, and her long auburn hair brushed his shoulders and chest as she kissed him carefully, keeping her weight off of his injuries. He kept her there as long as he could, before the need for air forced them apart.
“Aslan,” he breathed, still holding on to her, as though she might disappear at any moment. “You’re really here.”
“I’m sorry. I’m so sorry,” she murmured, still close enough that he could feel her breath, see her eyes brighten suspiciously again. “I never meant to…how long was I gone?”
He smiled, crooked and rueful, swallowing tears of his own. “Oh, only twelve hundred years. Or so.”
She pulled back in surprise, eyes wide and startled. “Twelve…? Oh, by the lion, Tumnus, really? Twelve *hundred*- but it’s only been a year for me!”
There was silence as they both struggled to grasp this immense unfairness. While for Lucy, only a single year, a single spring, summer, fall, and winter had gone by, for Tumnus it had been twelve hundred years- an unimaginable span of time! Lucy could only barely begin to picture it; her single year of loneliness, multiplied twelve hundred times, seemed utterly intolerable. Yet Tumnus had lived through it, and…enough! Lucy shook off her miserable train of thought, blinked hard to clear the feeling of tears about to come (again! She was doing a terrible amount of crying today!) and rose just as Tumnus opened his mouth to speak.
“I have to stitch up your chest and set your collarbone. Don’t move!”
Reluctantly, Tumnus closed his mouth over whatever he’d been about to say and dropped his hand away from her arm, but he turned his head to follow her movements around the cottage, unwilling to let her out of his sight. She covered emotion with busyness, testing the temperature of the water she’d set over the fire, deciding it was hot enough, pulling the cauldron off (carefully, so it didn’t burn her hand. Oddly, she hadn’t lost the knack of swinging it out and grasping it with a rag wrapped around her hand just *so*, and not a drop spilled), and getting the clean cloths she’d gathered earlier. She settled herself and her supplies next to Tumnus, not meeting his eyes as she dipped the first cloth in the near-boiling water.
“Lucy.”
“Mm.” She still wasn’t looking at him. Tumnus frowned and reached up, wincing, to touch her face.
“Lucy, look at me.”
“Can’t.”
“Luce...”
“I’ll start to cry again, all right?! Just…wait.”
Tumnus reluctantly dropped his arm, then bit his lip against a yelp as the hot cloth pulled at the clotted blood on his chest.
“Sorry,” Lucy apologized. “I…it’s…twelve *hundred*- damn, I’m going to cry again anyway…”
She scrubbed gently but persistently, rewetting the cloth, not looking up. Tumnus could see her blinking furiously, trying not to drip tears on him as she worked.
“I hope this doesn’t start bleeding again once I’ve got it clean,” she murmured, voice cracking around buried sobs. “I wish I had my vial…”
Tumnus stayed quiet, biting his lip against renewed pain. He knew Lucy more than well enough to know that anything he said now was going to start her crying in earnest, and she’d hate that. We’re going to have a long talk about this later, though, he resolved. I’ve got so much to tell her…Aslan, that twelve hundred years was long.
He kept quiet as she cleaned the gash on his chest to her satisfaction, but yelped as she brought forth the needle and thread. This got a laugh, albeit a shaky one.
“Don’t be a baby,” she said, smiling at him (meeting his eyes again, he grinned to himself). “I’ve got to stitch this up or it won’t heal properly. Hold still.”
“While you stab me over and over again. Thanks awfully.” Tumnus sighed dramatically. “I’m sure I’ll endure it somehow.”
“It’s just pinpricks,” Lucy told him sternly, then bent to her task. “Baby,” she muttered as she began. Tumnus only grinned, then winced as she made the first stitch. It did hurt, but not badly; Lucy was quick and skillful and was done in less than ten minutes, leaving a neat line of knots closing the ugly gash.
“Now,” she said, briskly snipping the last thread as Tumnus blinked and gave a final wince. "You never did answer my question. What happened?"