"Oh, why did I let curiosity get the better of me?!" Hiccup yelled as he fled, Toothless now in front of him, Vithvarandi hot on their metaphorical and literal tails. The grid-like pattern of the lowest layer of caves was helpful in keeping ahead. Toothless turned almost randomly, and it was all Hiccup could do to keep up. They weren't lost, precisely, but Vithvarandi was too close behind them to turn around and head back the way they had come, towards the passage up.

It was clear Toothless had no plan, save for staying away from the form Vithvarandi had taken. Hiccup still didn't know why it had produced such an extreme reaction, but Toothless wasn't thinking straight, even now, so it was up to him. If he could even keep up.

The snorting breaths of Vithvarandi's powerful form were right behind them, the echoing thumps of padded foot and clicks of sharp claws resounding from ahead and behind, a disorienting assortment of echoes colliding and mixing around Hiccup.

To make matters worse, that whirlpool in his head had grown stronger, physically painful now. The emptiness at its center was expanding, apparently unsated without whatever it gained from him killing someone. He really didn't have long. Maybe long enough to get Toothless somewhere safer than here, if they could just get out of these Thor-forsaken caves!

Hiccup took charge. "Toothless, turn right!" He stumbled as he yelled, feeling Vithvarandi's breath literally on his heels. Looking back would be a big mistake, so he kept going. He knew full well that she wouldn't kill him. She'd just stop him from getting between her and Toothless.

Toothless veered right at the next intersection. Hiccup really hoped this place held to the grid pattern he had noticed. If it didn't, and some of the passages turned out to be dead ends, his reckoning on where they were would be useless. But he thought he had this layer figured out.

Above was a tangled mess. But down here made sense. A grid, a pattern. Two rings, an inner and an outer, separated by a door. But that door didn't seem like it had been passed. There had been dust on everything, including the dial. Which meant there were other ways between the inner and outer rings. He was betting on this place holding to symmetry.

"Left now!"

Toothless swerved to the left, a wing skidding across the rock wall of the intersection to a grunt of pain. Hiccup could hear Vithvarandi's larger form slam into the wall, a much louder snarl emitting from her direction. Toothless was just slightly faster in here, and Hiccup's size meant he was far more agile than either of them in tight corners, allowing him to keep up.

Ironically, the only part of him that wasn't aching or in some unnatural pain was his stump. His hands ached as if someone had burned his palms, he had something far worse than a headache at this point, and his stomach was cramping from nausea brought on, he had to guess, by the thing in his head killing him. His legs, however, were fine.

Hiccup could see a door illuminated by the moss. Not the door they had come through because this one was shut. His guess had been right. It was identical to the other, from what he could tell. This time though, they were on the inside. And, as he had noticed, like the other door, the latching mechanism was visible here. Visible, and therefore vulnerable. "Toothless, blast it!"

Toothless complied, blasting the door, trashing the visible machinery. He body-slammed the metal, running out to the outer grid.

Hiccup slowed for a second, searching the wall for a sundial. Vithvarandi had fallen a tiny bit behind, but he had about two seconds to do this and get out. He located it and pushed hard, before running after Toothless.

The sound of falling rocks smashing through a thin sheet of stone and blocking the passage behind them was music to Hiccup's ears. The startled and very undignified squawk emanating from the other side even more so.

Toothless ran back and grabbed him, apparently no longer content to have Hiccup run now that there was a moment to spare. Hiccup crouched, just barely not hitting his head at the height of Toothless's bounds. Directing his friend wasn't necessary now. Toothless knew where the exit into the rest of the cave system was.

Given how the place was laid out, Vithvarandi would be by necessity forced to locate one of the other doors, which Hiccup had correctly deduced were located one in each wall separating the inner and outer grids. She would have to go the long way around. But not that long.

Toothless raced through the end of the passage, passing the dead branch Hiccup had left at the beginning of the moss. From here on out, it would be pitch black. Hiccup was grateful one of them had night vision.

That didn't make it any less scary as they tore through the irregular tunnels, now veering in what Hiccup would have sworn were random directions, if he didn't know the tunnels really were that confused and intricate. Toothless was so effective running through that Hiccup had the disorienting sensation of them both running blind on a large open field. It didn't feel like they were underground anymore, because to Hiccup there were no walls. Just pitch black, echoes, and the dragon beneath him who seemed to know where they were going.

After a few minutes, Hiccup began to hear other sounds. Another set of echoes. A roar, not nearly as distant as he'd like.

Toothless whined, veering away from the roar, which Hiccup realized in dread had come from the side, not behind them. They didn't know these tunnels. Vithvarandi did.

Another roar, this time closer. Toothless ran straight away from it, at an angle Hiccup assumed accommodated the tunnel they were currently in. His heart sank as the tunnel did, but there was no helping it. Vithvarandi was herding them now.

A snarl, from close on the right. Toothless fired a plasma blast, jolting in a different direction.

Nothing. Silence, save for the noises of Toothless trying his best to get away.

The world was fading, whether as an illusion brought on by the darkness or an unhappy side-effect of his oncoming demise, Hiccup didn't know. He closed his eyes, unwilling to stare into the darkness any longer. The world shrunk until it consisted of the sounds of Toothless, the smell of the cave, and Toothless running beneath him, saddle and scales. Hiccup began breathing through his mouth, trying to ignore the smell of the cave.

A moment was spared to regret all of this. Everything after encountering Vithvarandi in the village. If he had just pushed ahead and not stopped to rest, life could have gone on like normal. Things had been going so well. And now, here they were. He was dying, Toothless was in imminent danger of death. No one would know what had happened to them.

Stoick might think he and Toothless had just run off. Or that they had died somehow. Hiccup wasn't sure which was worse. His father's worry, or his father's disappointment.

Astrid. She hadn't been particularly friendly recently, but that was probably his fault, somehow. She would have the same options as Stoick on what to believe. It hurt that he wouldn't even be able to say goodbye to either of them.

And what of his best friend? Toothless deserved so much more than to die here, added to some morbid collection of bodies to be used at will. This was Hiccup's fault. Both that they were here, and that Toothless wouldn't be able to escape once he was dead.

That time was coming, slowly but surely. He was kidding himself if he thought they'd make it to another island. The closest one was several hours away. The way he felt now, he didn't have hours, he had minutes.

He was jolted out of his thought when Toothless roared in pain, jerking into a side-passage. Hiccup hadn't seen Vithvarandi leap out of the darkness and cut a gash in Toothless's side, but he definitely could feel how Toothless's gait faltered now. He could hear his friend's gasps of pain. They were slowing down.

When Toothless stopped, Hiccup instinctively knew they had hit a dead end. Emphasis on dead. His hands hurt now, beating in time with his head. Indeed, as he opened his eyes, he realized those scars on his hands were literally glowing, a blue light that helpfully illuminated the rock wall in front of them.

If this was to be the end, so be it. Hiccup slid down, getting in between Toothless and the rest of the passage. He still held both knives. One was that original long hunting knife, and the other was a much lighter, thinner one. One made for throwing more than actual combat. He held the hunting knife at the ready, and the other behind his back. His palms glowed from around the hilts, letting off just enough light to see the silhouette of Vithvarandi in front of him, staring silently. Waiting.

He didn't have much time left. But maybe time for one last gamble? A glance behind him showed that Toothless was ready to go out fighting, though he was still visibly cowed by the sight of the other Fury.

"Stand down, bud." Hiccup tried to make his voice stop quivering. He met Toothless's eyes, hoping his friend would get the message.

Toothless relaxed slightly. That was the best that could be expected, given the circumstances. Hiccup turned to Vithvarandi. "I might have changed my mind. I don't want to die."

Vithvarandi warbled curiously. Hiccup could finally tell from that neutral sound that her current body was indeed male. He was pretty sure a female Fury's voice wouldn't be that much deeper than Toothless's voice usually was.

"Can I talk to you?" Hiccup lowered his hunting knife, angling it towards Toothless in a motion only Vithvarandi could see. "I want to make sure I don't mess this up."

After a long moment, that now-familiar plume of black flame reemerged, retreating to reveal the woman that Hiccup had seen before.

Vithvarandi smiled. "I knew you'd see sense. There isn't much to it. Just kill him with it. Ideally as painlessly and quickly as possible."

Hiccup was slowly moving his other hand, resetting his grip on the other knife. "Why does that matter?" He was stalling for time.

But her answer genuinely surprised him. "You don't just get the body. The memories come with it. Better not to remember a slow and agonizing death. Especially with the first form you take." She shook her head. "Well, go on. He trusts you, even now. That should make this easy."

Hiccup half turned towards Toothless. "I don't like killing." He met Toothless's eyes. "But for this, I'll make an exception."

"To save your own life. It's understandable." Vithvarandi nodded solemnly.

Hiccup smiled darkly. "No, I fully expect to die." With that, he turned and slung the throwing knife, aiming for Vithvarandi's heart. This definitely wouldn't count as a kill for the purposes of whatever this thing in his head was, but hopefully it'd knock her off balance long enough to get them out.

Whether or not it would have counted was rendered irrelevant as the knife struck Vithvarandi's shoulder. She recoiled and gasped in pain, but it clearly wasn't a killing blow.

Hiccup drew another knife from his back holster, charging her while she was-

A plume of black fire slammed him back. Apparently, the transformation concealed a still very tangible body within the opaque flames. He was just grateful his clothing didn't catch on fire. Those black flames burned like fire, despite their unearthly appearance, and almost seemed to push him away.

Vithvarandi roared in rage, eyes burning with fury. Hiccup had a split second to realize she was pouncing, mouth open and teeth sharp. Any apparent reluctance to hurt him was gone. At least this way he'd go out fighting. If anything counted in getting someone to Valhalla, death by a shapeshifted human in the form of a Night Fury definitely would.

Toothless roared in helpless fear as Vithvarandi crashed down on Hiccup, her full weight almost crushing him.

Silence ruled the tunnel. He was still alive. Vithvarandi twitched.

At that moment, Hiccup realized what had happened. She had impaled herself on his hunting knife, at the same time as she cut her own throat open on his other dagger. Both done in the haste to attack, done by her own force and speed.

Hiccup felt a strange pressure in his palms, and he exhaled as the immense pain that had been building in his head abated. Blood ran down the knives.

A moment later, Vithvarandi's body crumbled. Hiccup could only watch in shock as the massive Night Fury broke down in front of his eyes, crumbling into an immensely fine black powder, reminiscent of ash but too dark to be just normal ash.

Toothless growled, eyeing something in the tunnel.

Hiccup looked up to see... Vithvarandi. The body of Hilda, more precisely. Glaring hatefully at him from a few feet away.

She spoke. "That was not at all what I meant." Her livid expression was oddly amusing on the young face she currently possessed. "Neither of us knew what that would do! It's never happened before! You could have somehow killed me for good, or it might not have counted!"

Hiccup shakily stood, brandishing the bloody knives. "Let. Us. Leave." He wanted off this horrible island, away from this woman.

Vithvarandi laughed, stepping aside. "You don't get it. I could kill you both. I'm nowhere near done. But there's no point."

Hiccup pulled at Toothless, trying to get his friend to walk past Vithvarandi while still pointing his knives at her. "No, there isn't." He was struck with a spark of inspiration. "Find someone who actually wants all of this." Ideally, she wouldn't. Another immortal mass-murderer was a bad thing. But he needed her to dismiss him, to forget about them both.

Vithvarandi considered him. "Maybe. But I only have one try left. If that fails..." Her expression was thoughtful. "Then we'll see." She disappeared into the darkness.

"Come on bud, we need to go." Hiccup laughed sourly as Toothless snorted, grabbing him and resuming their now painfully labored run. "Yeah, I know I don't have to tell you twice."

The escape from the tunnels went without further incident. Further confirmable incident, that was. Hiccup was pretty sure Vithvarandi was watching them from places unseen. Nevertheless, he had never been so happy to see dust, half-dead trees, and thorns. After what they had been through, those things felt downright benevolent in comparison.

Without hesitation Toothless leaped into the sky, fleeing that island as fast as he wings could take him, still dripping blood from the shallow gouge in his side. Together they fled, alive. If nothing else, alive.

O-O-O-O-O

Toothless dropped out of exhaustion on the first sea stack within the now comforting obscurity of the fog surrounding the abandoned nest. He moaned, curling around to lick his wound. Hiccup hurriedly took the saddle and prosthetic off, making his friend comfortable in any small way he could manage.

During that time, after they had both settled down, the reality of those last few moments began to set in. Hiccup caught Toothless casting him sideways glances.

The level of discomfort, almost fear, in Toothless's eyes almost broke Hiccup. He scooted closer, hugging his friend. "We're fine. You're fine. I don't think I'm going to die in the immediate future." The other side of that fact was one he wasn't ready to deal with yet. That spot in the back of his head was still there, no longer pulling. Just existing. He refrained from thinking about it.

Toothless rumbled cautiously, before whining and closing his eyes.

"I wish I knew what was bothering you." Hiccup smiled sadly. "You know, despite the lady who can apparently turn into dead people at will." It was pretty depressing that the only other Night Fury Hiccup had ever seen was technically dead.

That line of thought brought him back to ideas he'd rather not follow. He closed his eyes, still hugging Toothless's large head. "We'll be fine. Get some rest." It was past midnight, he had noticed, before they entered the fog. "Tomorrow, we can go back to..." He didn't want to stress Toothless now, of all times. "The cove." That place was safe, but still a bit private. They could recover more there.

He realized he had sheathed both knives. The one he had thrown was still... Well, he had never heard it hit the ground. It must... still be in Vithvarandi's shoulder? The shoulder of that body, anyway? Odd. Either way, he was immensely grateful Toothless had insisted he so arm himself those weeks ago.

Though, the use to which he had accidentally and intentionally put the knives to was one he could never have predicted. Throwing with intent to kill, and missing. Killing by pure accident. A Night Fury, of all things.

"Gods." Hiccup whispered quietly, so as to not let Toothless hear the bitter realization he just had to voice. "I killed a Night Fury." The paradoxical horror of that statement made him laugh bitterly. Of course, he killed a Night Fury by accident, now of all times. Now that it was the last thing he wanted to do. Before everything, this would have been a dream come true. Now, it was a nightmare.

They woke sometime the next day. Both were restless and unsettled. Needless to say, they left quickly.

Toothless was still eyeing Hiccup strangely, but he didn't protest their departure. The flight was smooth, as always. Both parties were left with ample time to think. Hiccup tried to not think, which was unusual for him. If he had his way, they'd both forget about what happened on that island.

Toothless swerved away from Berk, circling around so as to not be seen by anyone around the village, dropping into the cove with what Hiccup could have sworn was a sigh of relief.

The cove was peaceful, as always. Verdant greenery mixed against the backdrop of the light grey cliffs and pure blue water, reflecting the cloudless sky above. It was a beautiful Spring day, a rarity on Berk. Hail and rain were far more common in the Spring.

It served as a jarring juxtaposition to the mental turmoil Hiccup was experiencing. Here, in a place he had always associated with peace, his mind was in turmoil, no longer entirely his own. That little space Vithvarandi's actions had created was still there, a void in the back of his head, existing silently.

Now that they were somewhere safe, Hiccup felt he had to figure this out. He forced himself to go over what Vithvarandi had said, leaning against a stone outcropping. Toothless was drinking from the pond.

Seeing his friend brought to mind that Vithvarandi had wanted him to kill Toothless. Why? To take his form. Or else he would die.

But he had chosen death instead. Vithvarandi had, once convinced of that, decided to kill Toothless herself, as payment. All of this tied into what she had explained.

The issue was, he wasn't dead. And by Vithvarandi's logic, that meant he had killed her. That body, anyway. So what, exactly, was he now?

He turned his hand over, staring at the scars on his palms. These marked him and Vithvarandi the same. By that logic...

An internal war raged within Hiccup. Morbid curiosity fought horror. That void in his head begged to be mentally investigated, looked at. He didn't doubt there was something there. But this ability felt wrong, and no wonder. If he could get rid of it, he'd do so without hesitation. But from everything Vithvarandi had said, that wasn't possible. Was it better to ignore this new part of him, or to understand it?

The real question was, did he trust himself?

There was a practical side to this too. He needed to see exactly what had happened. Vithvarandi had never explained the steps after killing to stabilize the ability. Maybe because he had killed her, in an already dead body, it didn't fully count?

That would be the best case scenario. Not going to die, but not given the ability either. Hiccup clung to that, suddenly certain that was what had happened. He quickly focused on the void in his head, hoping to see that it was as empty as that theory suggested.

Big mistake.

The last two things he saw were heartbreaking and terrifying, respectively. Toothless, staring at him in utter horror, and a stream of dark blue fire flooding from his palms, crawling up his arms at lightning speed. All went black, or more accurately, all went blue as the flames enveloped him.

What had he done?

Author's Note: Last cliffhanger for a while, I promise. Well, assuming you don't take the ending of next chapter as a cliffhanger. It really isn't, but who knows. Also, I will say now, next chapter is not what you are likely expecting. At all.

Speaking of expecting things, credit to toothlessgolfer for obliquely calling the resolution to Hiccup's dilemma, though I will say that what you implied is not entirely correct. Exactly what you did not predict will become apparent in the next chapter.