A/N: Hello everyone! So sorry about not posting, but I'm gonna make it up to you! First up, more on the 100 prompts challenge. Nice long crossover for you.

Disclaimer: I owe nilch. Nothing.

The days that follow

Hikaru Sulu had always kept to himself, eyes down, working hard. That's what everyone said about the young Asian. Intelligent, hard worker, but he never talks or interacts. Even on board the Enterprise, the man was quiet and never made eye contact with anyone. But he had good reason not to. Looking at himself in the mirror, he inspected for the millionth time, the silver flecks in his irises. A manifestation of his mutation. Holding his left hand up, he watched as vines grew out of nowhere and snaked around his fingers.

"Evolution…" he muttered. "Being able to grow and control plants isn't human evolution." He sighed and returned to the bridge.

Hikaru had sat on that bridge countless times and never caught the eye of the young Russian navigator, Pavel Chekov. But today, it seems, was different. As he looked up to plot some co-ordinates, his eyes locked with those of the young Russian's. Jaw dropping, he searched the bright blue eyes… bright blue and flecked with gold.

After their shift, they met up in a quiet corridor.

"I… you… I em nyet alone…" Pavel whispered, gazing into Hikaru's eyes. Hikaru shook his head slightly, unable to tear his own eyes away from Pavel's.

"No… I'm like you… A mutant." The Russian smiled softly and on impulse, grabbed the pilot's hands. Slightly surprised but happy, he smiled and interlocked his fingers with Pavel's, vines sneaking over them. The boy's eyes lit up as he looked at the vines and shadows curled around them.

"Shadow…" muttered Hikaru. "Ash and Shadow." Pavel's eyes flicked back up to the pilot's.

"Heeku eend Pasha. Esh eend Shedow." Impulsively, Hikaru leant down and kissed the boy gently. Pavel kissed back just as gently. As they pulled apart, the shadows leaped and an ash tree sapling grew out of nowhere. Pavel giggled and the shadows died back down. Hikaru blushed at the sudden appearance of the tree and it disappeared. They smiled at each other, happy in the knowledge that they would never be alone again.

They managed to keep their secret between them until one fateful mission with Spock, Kirk and McCoy. They had gone down to a planet for routine checks on the settlement there and found everybody murdered by some sort of beast. Spock and McCoy had been scanning the bodies when Kirk, having been on guard, yelled,

"EVERYBODY RUN!" He came pelting through and began to run across the dry terrain, the others at his heels. There was a roar and Hikaru spun to see a huge beast, at least 8 feet tall, clawed and looking very angry. He squeaked and grabbed Pavel's arm, dragging him along as he ran faster. As the little group darted over the dusty land, the beast began to catch up to Pavel who was at the back of the group. Without warning, he screamed and the crew spun just in time to see the beast pick Pavel up with its teeth. Automatically, Hikaru slammed his hand on the ground, roaring and the beast was engulfed in prickly vines and bushes. It howled in pain and Pavel fell from his jaws, the shadows swooping around to catch him. Hikaru snarled, flicking his hand and the vines obeyed him, wrapping around the beast's throat. The vines snapped its neck and it fell down dead, the vines disappearing. Hikaru ran over to Pavel, scooping the boy up.

"Pasha!" he sobbed.

"H-Heeku…" whispered Pavel. "Your eyes… Zhey eer seelwer… all seelwer. He nodded slowly.

"Yeah. They do that when I get angry… Hang in there, Pav. You'll be fine." There was blood all over Hikaru and Pavel but neither of them seemed to care. Standing, the dark-haired man turned back to McCoy and Kirk who looked awed and slightly scared. Spock just raised an eyebrow.

"McCoy," Hikaru snapped. "A little help?"

"Yo-Your eyes, kid…" He rolled said eyes.

"Yes, my eyes are silver. Now, I think that Pavel's current state is a little more troubling than the colour of my eyes!" McCoy hurried over and took Pavel from Hikaru's arms. The Asian man stalked over to Kirk and Spock.

"We need to get to shelter. There is a forest exactly 1.97 miles from here," he said shortly.

"And how do you know that, Lieutenant?" asked Spock. Hikaru turned his silver eyes on him.

"I can feel it." Usually, Spock would have argued with such an illogical answer but Hikaru's eyes were unnatural and began to worry Spock.

"Okay," agreed Kirk. "Lead the way, Sulu." Hikaru nodded curtly and ran back to Pavel and McCoy.

"Pasha?" He asked and Pavel looked at him weakly. McCoy stood.

"He's gonna live. Give him time to recover," he said gruffly, not looking at Hikaru. The pilot nodded and picked up the boy.

"Pasha… how do you feel?" The navigator smiled weakly and stroked Hikaru's cheek.

"Your eyes eer back to normal… deed I ewer tell you how beauteeful zhey eer?" Shadows laced around Pavel's fingers and he smiled.

"I love you, Shadow."

"Eend I lowe you Esh." Hikaru smiled gently and began to walk towards the forest, carrying Pavel. Spock, McCoy and Kirk followed him.

Soon enough, they reached the forest Hikaru spoke of and knowing that they had lost their communicators in the commotion, they voted to stay here until morning and sort something then. As soon as Hikaru entered the forest, his eyes lit up, flashing silver and Pavel chuckled.

"Leeke eet, Esh?"

"It's my element, Shadow. It's where I belong." Pavel chuckled again.

"Da… meny shedows here…"

"Good for both of us then…" murmured Hikaru. He walked over to a large tree and laid a hand on the trunk, vines spiralling around his hands. He breathed deeply, eyes going silver as he transferred some of the tree's life force to Pavel, healing his wounds. Pavel gasped as the transfer was made, his eyes going gold and the shadows rising up. Gently, Hikaru put him back on his feet.

"How do you feel, Pav?" Pavel was silent for a moment and then he said,

"I feel… sefe and heppy." He hugged Hikaru tightly and the pilot wrapped his arms around the boy. They walked back over to where Spock and Kirk were trying and failing miserably to put up a tent.

"Let me sort shelter," said Hikaru and they stood up. McCoy was frowning at Pavel.

"Vhat?" asked the navigator.

"Five minutes ago you were too weak to stand… now you're walking around like nothing happened."

"Zat ees Esh for you. Let heem explain." Pavel shrugged.

"Ash? Who's Ash?" asked Kirk.

"I'm Ash," replied Hikaru. "It's my mutant name. Just as Pavel here is Shadow. You ever heard of the mutant phenomenon?" McCoy nodded.

"Yeah… but I thought all of the mutants died out."

"Zhey deedn't, eet seems," said Pavel. "Es Heeku eend I eer mutents. Mutents eend proud." The Asian chuckled.

"Yeah. I'm Ash and I can control plants mainly… I can grow them." He flicked a hand and a small ash tree appeared. "Shape them." Moving his hands again, he created a shelter big enough for the lot of them out of the nearby plants. "And absorb their life-force, which is how I healed Pav." He chuckled at their awed faces and Pavel giggled.

"Da. Eend I em Shedow. I cen control eend used ze shedows…" He flicked his hand, suspending Spock upside down by his ankles using the shadows of the trees. Yelping, Spock blushed green as the others burst into fits of giggles until Pavel let him down.

"That was not funny and illogical," grumbled Spock. Sniggering, Kirk said,

"Oh lighten up Spock!" The Vulcan grumbled again before retreating into the shelter. Pulling Pavel into his arms, Hikaru watched Kirk and McCoy process the information they had been given. There was a long pause before McCoy spoke.

"Can I take a blood sample when we get back?" Giggling, Pavel and Hikaru nodded.

"Sure. We had been expecting you to ask that," the Asian said. McCoy grumbled awkwardly and slipped inside the shelter.

As the sun began to set, Kirk retreated to the safety of the shelter; Pavel had set up a shadow guard so that they couldn't be caught off guard by any creature. The others already asleep, Hikaru pulled Pavel close to him as they sat outside the shelter, watching the sky darken.

"Vell… zhees hes been en eenteresteeng day," murmured the Russian, laying his head on the other's chest. Playing with Pavel's curls lazily, the Asian chuckled slightly.

"You could say that, Pasha my love. You know… when that beast got you... I couldn't think. I didn't care that McCoy and Spock and Kirk could see me. You were in danger. I suppose… nothing matters if you're hurt or in danger. Just you." He fell silent and the boy nuzzled closer.

"Karu… Eet ees okay. I em here… safe. But… I remember vhen eet peecked me up and beet eento me, I zhought… I em goeeng to die. I em sorree Heeku but I em goeeng to die. Zhen you screamed eend ze beast vas cowered een veenes eend I knew… you sawed me."

"I'll always save you. Always. Because, I could never live without you. I love you, so damned much," Hikaru whispered, tightening his hold on the other.

"Eend I lowe you. Heekasha, I lowe you so much." Pavel clung to him and kissed him tenderly. The dark-haired man relaxed into the kiss, hands in Pavel's hair. After a few seconds, they broke apart and smiled at each other, eyes full of adoration. Spock found them in the morning, fast asleep in each other's arms, covered in a blanket of leaves and shadow.