Set after the finale.
Two young cubs watched the sun set over the royal city of Thundera, back when it was standing great.
"The sunset is so beautiful. Isn't it?" A young female cub asked dreamily, leaning against a young male. The two were different cats, a leopard and a lion.
"Yeah…" The male lion cub said, possessing a sad mood.
"Is something wrong, Lion-O?" The female leopard asked. He turned away but she leaned in closer. "It's your family again, right?" Her voice was gentle with a hint of teasing, along with a black brow raised amusedly.
He sighed and turned back to her. "My father scolded me and compared me to Tygra again. He treats me like I'm the adopted son!"
Just when he was about to lose his temper, a gentle hand grabbed his shoulder, the gentleness quickly calming him down. Only his best friend understood his burdens.
He sighed again. "He wants Tygra to be king. Everyone does. Then what am I doing here? My mother died giving birth to me. Tygra was heir before I came along."
"It wasn't your fault. I never knew my parents but living on the streets makes up a hard life for me, I guess."
"How can I be a great king like my father?"
"You will. There's no one better to be than yourself, Lion-O."
Young Lion-O smiled at her, feeling his happiest in her presence.
"We'll be together forever…right?" She asked him, unsure and tilting her head.
He continued to smile. He cupped the side of her face. "We will. I promise."
She leaned in his head, their eyes locked in a longing gaze…
"There you are!"
The cubs jumped up in surprise.
"Tygra!" Lion-O exclaimed.
The tiger prince was angry and advancing close. Lion-O's friend froze because she was scared of Tygra.
"You!" Tygra snarled at her, making her even more scared and her fear forced her to run.
"Run, Leopera!" Lion-O shouted, his hand helplessly reaching out was all he could do…
"Run, Leopera!" Lion-O cried out in his sleep, accidentally waking up the sleeping cats. Snarf jumped up and landed on his lap.
"Huh, what, who, where?!" Kat exclaimed, leaping up, ready for battle. His sister Kit shrieked.
"What in the blazes?" Panthro wondered out loud.
"What are you screaming for, Lion-O?" Tygra growled, irritated.
"Sorry," Lion-O apologized, touching his head. "Just a dream."
"Well, keep it to yourself." Panthro grunted and then propped down on the ground, snoring like the Feliner's engine.
Kit and Kat copied him, dropping down and fell fast asleep.
With Snarf nestled at his side, Lion-O shifted in his bedroll, about to go back to sleep when he stopped by Cheetara.
"Lion-O, who is Leopera?" The cheetah asked.
Lion-O hesitated to answer. He wasn't sure how to answer. Tenderness crossed his face as he remembered Leopera. "She was my best friend…" He then shot a glare at his brother. "Until Tygra chased her out of Thundera."
"I did not chase her out of Thundera." Tygra retorted.
"You did! And that was the last time I ever saw her!" Lion-O's sudden outburst took Tygra and Cheetara by surprise. He sat down, arms crossed over his angry face.
Tygra sighed, knowing his brother was still hurt over losing the only friend he had, all thanks to him. "He never forgave me for that."
Cheetara shifted in his arms, turning around, kissed him in an effort to comfort him over his regret. He kissed back, feeling a little uplifted. The lovers broke apart and went back to sleep.
The next morning, the ThunderCats journeyed through a jungle, following the Book of Omens in pursuit of the final stone. Unfortunately the Feliner couldn't get through the thick jungle any longer.
"We have to fan out and find a route." Lion-O announced.
Kit and Kat ran off with Snarf. The kits took to the trees, having a laugh as they swung on vines and branches. But then Kit lost her grip.
"Kit!" Kat yelled. He dived down, falling along with his sister and Snarf down, and ended up trumbling down a cliff.
The rest of the ThunderCats heard the kits' screams.
"Is there a time those kittens aren't in trouble?" Panthro grumbled.
The kits fell roughly onto the ground. Snarf, rolling down in a ball, collided into Kat's back, earning an 'oomph' out of the male cat. Kit sat up and rubbed her sore back. She noticed that wherever they were, it was coated heavily with a fog.
"Kit? Kat?"
"Where are you?"
"Down here!" Kat hollered back.
"Don't worry, we'll be right down!"
Kat nodded and helped his sister up. "Are you okay, sis?"
She nodded. "Uh huh."
BAM!
Suddenly something ran into the kits. Snarf was thrown, a figure got their limbs intertwined with Kat and something else ended up on top of Kit. A round object wrapped in a cloth rolled away from the mess.
"Ow…" Kit moaned.
"Sorry…" Someone said.
Then Kit saw that she was touching noses with a dog pup that looked like he was her age. He was a Doberman Pinscher/Rottweiler-mix with a black body with brown on his muzzle, chest, hands and feet, and the triangular floppy ears of a Rottweiler. His yellow eyes were fixed on her, while he was blushing. He had a slender yet strong built, wearing a brownish-gold suit with short sleeves and legs, golden(!) armour plates on his shoulders, abdomen and knees, a familiar long brown open glove that topped with a spiked disk on his right hand, and a brown cloak which covered them both.
Kit thought he was cute.
"What hit me?" Kat groaned.
He looked, finding a young, female lynx girl tangled with him. She had short curled-inward orange-red hair with black spots and tips. Her eyes were spring-green and framed with long white eyebrows and eyelashes. Her slim body was coated with tan-coloured fur, with red on her hands, tufts of black hair on the tips of her ears, and a distinct fluff of fur on her chest with a black bow-like marking on her collarbone. She wore a light-red vest over a sleeveless black shirt, both going over her hips, with a brown leather belt with a grey metal buckle around her waist, a red-brown knee-length skirt, black gauntlets on her arms, a necklace with an ivory claw, and long black spat-like covering on her legs.
He grinned. "Hi!"
The lynx kicked him in the face in response. She catlike hopped onto her feet and ran off, grabbing the brown cloak to forcedly pull the dog off of Kit.
"Hey!" The dog yelped. The lynx ignored him and just dragged him off, snatching the bundle as they went out the mist and into the jungle.
"Wait!" The twins hollered, chasing the lynx and dog.
Just then, the ThunderCats appeared.
"Kit, Kat?" Cheetara called.
"Snarf, where are they?" Lion-O questioned his pet.
Snarf beckoned to where the kits ran off.
Lion-O heard the distant yelling of the twins. "Let's go."
"Wait! Hold up!"
"We're not gonna hurt you!"
Kit and Kat chased after the runaways all over the jungle, running after them with speed, even when they tried to lose them, the kits still caught up.
The lynx sniffed and stopped, forcing her canine companion to stop as well.
"Got ya!" Kat lunged but the runaways dodged, leading him to smack right into the ThunderCats.
Lion-O caught him, grasping his hands on the young one's forearms. "Kat! What the-"
"Wait! Stop, please!" Kit ran passed her team, still chasing after the runaways.
"What in thunder is going on?" Tygra questioned.
"We found a cat and dog from the mist, but they keep running away from us!"
"I'll get them." Cheetara said and she flew off in hot pursuit.
"Yikes!" The dog yelped when he took a glance behind.
"What?" His feline friend snapped.
"We have a cheetah on our tails!"
"We don't have tails but I know what you mean. Cut through here!"
They took a right, dashing through trees to throw Cheetara off. But Cheetara pulled through, chasing them at high speed. The two tried to slip around a tree, but Cheetara had beaten them.
She cut in front of them, causing the two to crash into her. She grabbed the pup and kit before they could ran off.
"Calm down, I'm not going to hurt-"
Look out!" The pup pushed her down, narrowly missing a spear.
"Thanks. Hide." She pushed the two aside and got up, drawing her staff for battle.
Sure enough, there were cats like herself, but of different species, coming at her, wearing tribal clothes and gold jewellery. She swiped her staff, feuding off the offenders.
"Cheetara!"
Her mate swooped in, attacking with his whip.
"ThunderCats, ho!"
The lynx girl gasped from her hiding spot. She took a peep from behind the big tree root, seeing the ThunderCats fighting. But then one of the attackers threw a grenade to the ground, dark smoke coming out.
"It's knockout gas!" Panthro gasped before coming drowsy, and then dropped.
Cheetara fainted from the smoke. Tygra caught her and held her as he stumbled down to his knees and lay on his side. Kit and Kat tried coughing and covering their mouth but they fell victims to the gas. Supported by his sword, Lion-O gathered Snarf up before he fell to unconsciousness.