In "The Liar Ball You Don't Want", Lightning and Bottle are both excited for Donut hosting his first Cake at Stake.
In "The Liar Ball You Don't Want", Lightning explains to Bubble that Loser was everyone's hero, so they're acting murderous cause they don't know what's right anymore. He then decides to nab the Liar Ball from everyone else, which Bubble cries out for him not to.
In "Return of the Rocket Ship", Lightning is concerned for Bubble when she is holding up all of Team Ice Cube! and works with his team to save her from Beep also falling on her. He is shocked when Flower ends up popping Bubble after their efforts to save her.
In the first and second seasons of BFDI, Lightning and Cloudy were usually paired together. Lightning appeared in Cloudy's joining audition in "The Reveal", and he also killed Pin with Lightning in "No More Snow!".
Status: Unknown (Possible symbiotic relationship)
In "Getting Teardrop to Talk", Lightning tells Snowball to team up with Fanny because of her "murderous" attitude and for how she hates everyone. Later, Lightning ends up zapping her when Pencil tells him to.
Status: Possible enemies/Neutral
Lightning and Flower are most likely enemies. Although Bubble told him to do what he felt was right after Match told him to zap Flower in "Getting Teardrop to Talk", he zaps her anyways, twice. This also happened in "Why Would You Do This on a Swingset", after Flower had enough of him clarifying the challenges.
In "Get to the Top in 500 Steps", however, they appear to be slightly more friendly, as Lightning smiles at her when he catches her after she falls off the 500-step staircase.
Status: Enemies, possible friends as of BFB 11
In "Get to the Top in 500 Steps", Four threatens to kill the flyers, Lightning included, if they try to do the contest.
In "What Do You Think of Roleplay?", Lightning doesn't believe Four and X are as fine as they say they are since they were behaving differently.
Status: Minor enemies
In "The Liar Ball You Don't Want", Marker and Lightning can't figure out why Donut isn't appearing on their camera until Lightning realizes that he was zoomed in on his hole.
Match and Pencil
In "Getting Teardrop to Talk", Pencil and Match manipulate Lightning into zapping several characters. He calls them maniacs at first for this but seems to have no problem with being told to zap Fanny later.
Status: Possible friends on his side
In "What Do You Think of Roleplay?", Lightning, disguised as Pin, asks Needle how long she's been under the side effects of the Photo Cake. Needle points out how Pin was there when it happened causing Lightning to get caught as the impostor.
In "The Liar Ball You Don't Want", Lightning indirectly zaps Pie and causes her to fly away from the liar ball.
In "Get to the Top in 500 Steps", when Fanny and Snowball are arguing, Lightning can be seen leaning on Ruby's head.
In "Return of the Rocket Ship", Ruby calls Lightning "thunder". Lightning gets confused and corrects her that he's called "Lightning". Ruby tells him that it's the same thing and Lightning quickly replies it isn't. He then says it would be like if he called her "shatter sound". Ruby angrily replies that he didn't need to death threat her and that if he didn't want to dig he could've just said so. Lightning is caught off guard by her anger and clarifies that he really wants to dig and digs a massive hole in the ground to prove it.
Status: Likely friends
Lightning and Snowball are likely friends as they are often seen near each other with Lightning leaning against Snowball. In "Getting Teardrop to Talk", Snowball picks Lightning to be on his team because he's killed 'dozens' of people. Lightning suggests that Snowball should team up with Fanny because of her "murderous" attitude. Later, when Lightning zaps Flower, Snowball angrily asks why he won't zap him instead, Lightning just gives him a look in return.
In "What Do You Think of Roleplay?", they sit together during the Cake at Stake.
Status: Good friends
Status: Possible enemies
In "What Do You Think of Roleplay?", Lightning feels insulted by the fact that his team is taking so long to figure out that he's been replaced.