I love the G3 Rahkshi concept, if you couldn't tell. Now here's my version of the origin story of Turahk.
"I'm just useless," the Ta-Matoran blacksmith Tahu moaned. "I'll never be good for anything." He picked up one of his, quite obviously failed, blacksmithing projects; in theory, it was probably a sword, but it looked more like a baby Muaka's chew toy. He tossed it across the room. Toruhm quickly leaned to the left as the flew out the window into the nearby lava stream. That scared him a little, but he would never admit it.
Tahu had been tasked with forging the new equipment for the island wide Kohlii Tournament, and hadn't been able to achieve anything. It would really help if he had elemental powers, which, as far as Toruhm knew, he didn't. In that respect, he was an outcast in Ta-Koro. In fact, he wondered why Turaga Vakama had even let him be a blacksmith, a job almost made for the control of Fire. The village lived in constant fear of Tahu accidently exploding something. But, here he was, and Toruhm was trying to do all he could to help him out.
"Tahu, take a breath things will get better," Toruhm soothed. He was usually too nervous to help someone out, but Tahu was his very old friend. He was fine here.
"You've been saying that for years, Toruhm. Nothing will ever change." He sat down on a rejected pile of shields.
"Tahu, you are the only Ta-Matoran to ever not have powers, at least yet. The Great Spirit must have something great in store for you."
"Then when is the Great Spirit going to reveal what it is?" he moaned. He looked at Toruhm, then back at the floor. "Just go tell Vakama that he'll have to find another blacksmith for the Kohlii Tournament. I'm giving up."
Toruhm solemnly nodded, and with a last look at Tahu, walked out the door.
This would be terrible timing for a change of plans; the Kohlii Tournament was only in three weeks, and this was promised to be the event of the millenia. Turaga Vakama would be upset, but understanding. In fact, that seemed to be his perpetual state.
As he was walking to Vakama's hut, he started on his shortcut, which should have been an official path, since all Ta-Matoran trekked it. A path had been carved out of one of the lesser volcanoes, with cut straight to the main village. It was also quite beautiful. The flame danced in there like no where else.
It was getting dark out, Toruhm noticed. He would never call himself a fearful individual, but he might have been. Now, he wasn't jumping at the smallest noises, but the dark still frightened him a bit. He had been robbed several times by unknown assailants on his way home before, so now he carried a knife with him at all times. And tonight it seemed unnaturally dark.
On the way, he noticed a larger-than-normal blood red Fikou spider. Toruhm jumped. He hated spiders. He had been afraid of them for as long as he could remember. And this one was no different. But, it almost seemed to be watching him now, as he walked. He quickened his pace.
He was inside the volcano now. Then, for some inexplicable reason, he stopped. Maybe it was something in the air, or a peculiar noise, but there was something different. And, as if on the wind itself, and gathering power with each syllable, he heard one word.
The voice sounded unnatural, and disconnected from anything. It felt evil.
"Nurhii? Is that you?" Toruhm asked. "Kapura?"
And then again, "Tooooruuuuuuhm."
"Who is this?" the Ta-Matoran asked. He was beginning to be very scared.
"A friend. A father-figure if you will."
Toruhm began to back towards the entrance, when he realized the very air around him became suffocatingly thin. The fire below the path started to dim. "You don't sound like a father-like."
"But to be sure, I am one..." the voice continued. "And you will come to know this soon."
Toruhm had had enough. He turned around to run for the exit, but there was no exit. Only darkness. He had walked this path hundreds of times. There had to be an exit there.
"You are afraid," the voice said, gaining more power.
"No. I am not afraid. Ta-Matoran don't feel fear," Toruhm shouted, unsheathing his knife, and lying his heart art. He had never been this afraid in his life.
"But you are. I can see it." The voice seemed to be coming closer. "You hand shakes. You are off balance. You sweat. You look behind your back, when you know no help will come."
"Stay back. I'm warning you!" He swung his knife to accent the statement.
Suddenly he heard a familiar skittering. The Fikou Spider he had seen earlier had found it's way into the cave. And it looked vicious.
"Your fear has betrayed you as a Matoran. But it will give you your greatest strength as my servant."
The Fikou Spider shed it's legs, and became slug-like. It pulsed and twitched, slithering ever closer to Toruhm.
"This is the Kraata. It will be your friend. And you will be my son. Rahkshi."
The only sounds after that were Toruhm's agonized screams echoing through the cave, so loud that no one could hear them.
"Hello?" The Captain of the Guard, Jaller, called into the cave. It seemed eerily quiet. He unsheated his sword.
"Jaller, oh thank goodness." It was the voice of Toruhm.
"Toruhm, where are you?" Jaller asked. He couldn't be seen anywhere. Suddenly, above him he saw movement. A giant creature was sitting inside the volcano. It stretched it's giant legs, and it seemed to be holding a giant staff, or spear, or something.
"Toruhm?" Jaller asked, feeling the blood rush out of his body.
The creature was fully in view now. It wore a blood red mask and armor, and had looked like an overgrown Fikou Spider. It's eyes had bloodlust in them. Jaller stifiled a scream, and was ready to fight it off. But with one swift movement, it knocked Jaller to his back.
"Oh, I am not Toruhm anymore. My name is Turahk," the transformed Toruhm drawled, "And you are afraid."