Lion-O is a Thunderian male, with moderately-long, wavy, scarlet-red hair, and ginger-orange eyes. Nonetheless, he will become the true Lord of the ThunderCats and afterwards guide New Thundera for a reign of peace and balance. Together with the New ThunderCats and Panthro's new vehicles he finally restored peace on Third Earth and found the Treasure of Thundera on his reconstructed home planet, he did indeed mature.ĭespite all this and despite his training later on the Book of Omens in the Wildstorm Comics, he still will have to endure his most difficult trials to defeat his nemesis Mumm-Ra since he will make a spell to make him age and become temporarily an elderly in the last arc of the comics: Dogs of War. But Lion-O had already grown from his past experiences enough to defeat all of these villains. At first, they proved too much for Lion-O, especially Tug Mug's gravity attacks (being one of the few to tear into pieces the Sword of Omens) and Alluro's mind magic spell.
The Threat of the Lunataks and The Treasure of ThunderaĪ weakened Mumm-Ra asked for the mutants help to free the wicked Lunataks, who were in a lava crust prison. This medallion was taken away by Mumm-Ra, who believed it would give it absolute power, but conversely concluded with the apparent destruction of Mumm-Ra (this is the "second death" of Mumm-Ra, in fact). Jaga managed to ask for the Star of Thundera, who was entrusted to Lion-O as a medallion to not be affected by the dangerous Thundrainium. This was the first time Jaga the Wise directly helped Lion-O since Grune the Destroyer appeared (in fact, this is the second time the sabretooth lion was summoned). Lion-O is still trying to surpass many types of obstacles, from being rescued from a boiling sea water due to the Berserker's ship cannon, then surviving an avalanche made by the new Mutant's machine - The Iron Fist - then falling from the sky from Shiner's cruise starship, later being trapped in Mumm-Ra's mummies trap bandages, and at last ending in Fire Rock Mountain, to have a one-on-one duel against the samurai Hachiman, who was tricked by Mumm-Ra to fight the young leader once more. A massive cast of returning heroes and villains were incorporated into the story to make it the most epic ThunderCats adventure yet produced.
In this TV movie, there were three new Thunderians introduced, who had also survived the destruction of Thundera. Interestingly enough, this will not be the end of Mumm-Ra, as established in the following movie, ThunderCats Ho! Lion-O is crowned the true Lord of the ThunderCats in an august ceremony attended by nearly every inhabitant of Third Earth.
Lion-O will ultimately triumph over Mumm-Ra in final trial ("The Trial Of Evil") in the heart of the villain's pyramid in which he discovers that Mumm-Ra, like any Egyptian mummy, is dependent upon his own sarcophagus. The Mutants are at all times a threat to the ThunderCats, and they attempted to interrupt Lion-O's trials -ultimately without success- to take advantage of this in an effort to leave the ThunderCats leaderless. In the latter half of the show's first season, Lion-O has to put all that he has learned to use in the "Annointment Trials," which consist of contests of strength, speed, cunning, and intelligence (this last is referred to as "mind-power" in the story arc) against each of the ThunderCats: Panthro, Cheetara, Wilykit and Wilykat, and Tygra respectively (complicating matters for Lion-O is the fact that he is required to be unarmed for the contests moreover, the rest of the non-participant ThunderCats are not allowed to assist him).
Although cunning and skillful, he is truly a child in a man's body, and throughout the series, must learn what it takes to become a true leader and gain true maturity. The now grown-up Lion-O assumed that this was the reason for his aging to adulthood, though he did not express any confusion regarding why WilyKat and WilyKit had not also aged as he had, which seems to indicate that he simply accepted it as a quirk of the capsules.
Coincidentally, such a malfunction did not occur with Wilykat and Wilykit, who were around the same age as himself, though as Lion-O recalls in the series' first episode, his mentor Jaga had mentioned that some aging does take place while in the Suspension Capsules in which he and the other ThunderCats were placed when their flagship was damaged. During this journey, he aged physically until he became an adult of age twenty-four this was due to the suspension capsule diminishing but not altogether preventing aging (" Exodus"). He was among the group of Thunderian nobles to make the trip to Third Earth in the flag ship of the Thundercats, when their planet Thundera was destroyed.