Like I said, here is the retconned version of Adventurous Anthros- (though this is just a prologue to show a bit of Panthro's past)

New Characters introduced- Lion-O, Tygra, Cheetara, Wilykit, Wilykat, Snarf, Panthro (Thundercats 2011)

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Crossing Over: When heroes unite
A Fanfiction written by TheAnnonymousKat on Furaffinity
The following fanfiction is a nonprofit project for fun, all aspects of copyrighted series including characters depicted in this fanfiction are owned by their respective creators and I encourage you to support the official release of those series. Also special thanks to my friend Ben Bandicoot for helping me with the writing on occasion and allowing me to use his character.

Prologue-

“That’s it! I’m done!” said Lion-O furiously as he pointed towards Tygra,
“If you have such an issue with how I lead then I’m done leading,” Lion-O added angrily. Cheetara seemed noticeably concerned with how the argument between the two brothers had escalated, they’ve disagreed in the past, but it had never gotten this bad,
“Fine by me! You’re a terrible leader anyway, I think we both know that I should’ve been the one to have been given the sword,” Tygra argued back. Lion-O then angrily took off his claw shield with the Sword of Omens within and threw it at Tygra, who caught it with relative ease, but the action still caused the thunderkittens and Snarf to flinch,
“Then take the sword! I’d love to see you do better as a leader! I’m done with all of you!” said Lion-O as he angrily began to storm off. Kit looked up in surprise before she ran over to Lion-O and grabbed ahold of one of his hands,
“Lion-O! Please wait!” Kit plead with tears in her eyes. Lion-O clenched his fist, and he was so visibly angry that the rest of the Thundercats were afraid that Lion-O was going to hit her in a fit of rage, though to everyone’s surprise he managed to calm himself before he gently slipped his hand out of Kit’s grip and pet her one the head,
“I’m sorry Kit, I can’t do this anymore,” said Lion-O softly before he continued walking away,
“So that’s it then? You’re just going to give up and let Mumm-Ra do whatever he wants? What about father?!” Tygra demanded,
“I’m still going to take down Mumm-Ra, but I’m going to do it without your help,” Lion-O replied as he kept walking,
“Without my help? That’s a laugh, you won’t last out on your own, especially without the sword,” Tygra replied,
“I’ll take my chances,” said Lion-O as he continued walking until he was out of sight.

Cheetara walked over to Tygra and slapped him across the face with tears in his eyes, clearly upset with how he handled the situation. Tygra averted his eyes from Cheetara, it was always hard to look at the one he loved when she was upset,
“I’m sorry…” said Tygra,
“I’m not the one you should apologize to,” said Cheetara,
“I can’t, I’ve grown up with him, I know how he is. He needs time to cool down before I can even attempt to apologize,” Tygra added. Tygra then took a deep breath and looked around them, they were in the middle of a wasteland, having recently lost their power stones as well as their hope caused Tygra to lash out at Lion-O and blame him for everything that happened to them, which turned into a shouting match, which lead to Lion-O storming off. Tygra then handed the claw shield and Sword of Omens to Cheetara,
“Can you return this to him?” Tygra requested. Cheetara nodded and took the items from Tygra, just as she was about to take off though, Snarf meowed at her, implying that he wanted to go with Lion-O. So after taking Snarf off of Wily Kat’s shoulder, Cheetara ran after Lion-O at her supersonic speed. The rest of the thundercats waited for several minutes in an uncomfortable silence before Cheetara returned empty-handed with a somber expression,
“Well?” Tygra inquired,
“He took the sword and shield… and Snarf… but he told me that he can’t come back so the Thundercats are disbanded,” Cheetara explained. Everyone was surprised at Cheetara’s news, especially Kit, who was still crestfallen from seeing Lion-O storm off like he did.

Tygra took a deep breath and looked towards Cheetara,
“Then I guess it’s up to us,” said Tygra,
“What do you mean by that?” Cheetara asked,
“We have to be here for Third Earth Cheetara, for our kingdom. It’s what Father would have wanted,” Tygra explained,
“What about your brother?” Cheetara asked,
“He’ll be fine, he has the sword and Snarf. I think it’s best if we allow him to go and do his own thing, he’ll eventually come back when he realizes how much he needs us,” Tygra explained. Cheetara seemed somewhat doubtful, but Tygra’s next question eliminated her doubt,
“Are you with me?” Tygra asked,
“Always,” said Cheetara with a faint smile, and an unbreakable trust in the person she loved most. Tygra then turned towards the Thunderkittens,
“What about you two?” Tygra asked,
“We can’t Tygra, we finally found our parents, they need us to stay with them,” Wily Kat explained. Kit said nothing, simply staring off into the distance where Lion-O had walked, as if expecting him to magically come back. Tygra turned towards Panthro,
“What about you big guy?” Tygra asked,
“Her Loyalty is to you, my loyalty is to my king,” Panthro explained,
“Your king ran off and disbanded the Thundercats,” Tygra explained,
“I know.. I don’t have an answer right now, I think I need to wander around for a while until I do,” Panthro explained,
“Suit yourself,” said Tygra with a sigh.

That was the last thing the former thundercats said to each other that fateful day. Tygra and Cheetara walked away in a direction opposite from Lion-O, WilyKat grabbed WilyKit by her hand and carefully led her along to the direction their parents were, while Panthro stood still for quite a while, watching his dear friends disappear into the distance. Panthro noticed a pair of his nunchuk on the ground a few feet away, so he stretched out his robotic arms to retrieve them. Panthro then started walking like his friends, in a different direction than anyone, he had no goal in mind nor anywhere in particular he wanted to go, though this seemed like the best option for him. After a few hours of walking, Panthro came across a strange distortion of space that seemed to ripple, the same ripple that he and his former team learned about recently. These ripples apparently act as doorways to other worlds, and Mumm-Ra had used one of the ripples to escape from their world and move onto the next, presumably to conquer it. After taking a deep breath, Panthro reached out and touched the ripple, not knowing where it leads, but knowing deep down that he was going the right way.

The ripples have existed for as long as time has flowed, countless worlds of many varieties exist and these ripples give those world’s inhabitants a chance to intermingle and interact with one another. For every light, there is a shadow and for every hero there is a villain, as a result of worlds becoming interconnected, both groups of heroes and groups villains from many different worlds band together in order to accomplish their goals. Due to the abundance of heroes, the majority of the worlds have decided to enforce a hero society to give the heroes certain guidelines to follow and make sure they aren’t doing more harm than good, and as a result of following these rules and keeping the peace, heroes are given monetary compensation as well as government paid room and board. Though the ripples can seem intimidating at first, and going through one isn’t always a good idea, like Panthro you can often find that the best option is crossing over to the next world.