Lil' Lighting is a slightly obese light orange Pembroke Welsh Corgi with creamy peach fur. He has cream-colored paws and a blue leather collar with a license of a lightning bolt.
At first, Lil' Lightning is a trusted ally and a good friend and sidekick to Thunderbolt.
However, he eventually became increasingly frustrated and extremely jealous of Thunderbolt's fame and attention from ladies (female dogs), as well as making him feel insecure and unappreciated, which is the reason Lightning was against Thunderbolt. Afterwards, Lightning secretly planned to get rid of Thunderbolt so he could take his place on the show (which would have become The Lil' Lightning Show) and steal the attention from him.
Whilst he is sweet, trusty, and precious, Lightning can also be clever, sneaky, and conniving. Even though he originally betrayed Patch and Thunderbolt, Lightning still shows a bit of remorse and genuine feeling (as well as redeeming qualities) when Thunderbolt fakes his death towards the climax of the film, crying for him and thinking he is actually dead (since he never planned to have him killed nor had a desire to do so), saying through tears, "Good night, sweet prince."
Lil' Lightning starts off as a supporting protagonist in the film.
Eventually, Lightning becomes jealous of always simply crawling in Thunderbolt's shadow, as well as Thunderbolt's rude and arrogant nature towards him. In retaliation, Lightning tricks him into running away by convincing him that the executives planned to permanently replace Thunderbolt with a younger dog. Thunderbolt believes this and begins to panic.
Afterwards, Lightning tricks the director into re-writing the show slanted towards himself. As he watches through the window, he laughs and teases a plush toy of Thunderbolt, asking him what he thinks of the "whole new direction" and calls him an overrated, overacting ham. He relishes in the thought of The Lil' Lightning Adventure Hour, thinking the title sounds good and teasingly asks the Thunderbolt plush toy what he thinks of it and snickers evilly to himself.
When news of Patch and Thunderbolt planning to rescue 98 Dalmatian puppies from Cruella De Vil reaches Lightning, he realizes that the deed will endanger his chance at fame. Afterwards, he reaches Patch and Thunderbolt in Cruella's hideout and convinced Thunderbolt not to use Patch's stealth plan, but to openly attack, and smirks as Patch and Thunderbolt enter the hideout. This results in Patch and Thunderbolt getting locked up by Jasper and Horace. Ultimately, Lil' Lightning reveals his dark nature (having betrayed Patch and Thunderbolt), angrily declaring that he is not Thunderbolt's "little buddy" and reveals to Patch that Thunderbolt is a "fraud" and doesn't care about Patch or his family; he just wanted "his name back in the papers." Then Lightning told Thunderbolt that what he said about him being replaced was a lie to get Thunderbolt out of the way and finally be out of his shadow by taking Thunderbolt's place in the show. With his plan carried out, Lightning escapes while laughing evilly, leaving Patch, Thunderbolt, and the Dalmatian puppies locked away.
As soon as the television filming of The Lil' Lightning Show began, Lightning was caught on the driving window of a double-decker bus ridden by Patch during his escape from Cruella, Jasper, and Horace. After the chase, Lightning was deeply saddened by Thunderbolt's "passing" and bursts out in heavy tears, bidding him "good night, sweet prince." Suddenly, Thunderbolt awakens, licks Lightning on the cheek, and allows the bus to move toward the villains, eventually sending them into the water, along with a van. Later, Lightning is taken away by the pound, all while trying to convince the police dogs that he was "helping" Thunderbolt since they were a team, to no avail. His popularity is lost as well, with a newspaper heading in the credits regarding him as the "unkindest cut of all."