Like everyone else, Leafy didn't like Flower because of her mean-spirted personality in BFDI. They didn't have any chances to interact again since until the split in BFB, which is when they slowly started to become friends due to Flower becoming noticeably nicer than before.
Episodes suggesting a friendship
In "Return of the Hang Glider", Flower decides to vote Leafy because she's a plant. She also slaps anyone who doesn't vote Leafy.
In "A Taste of Space", when Flower is forced to be X's garden, Leafy greets her and asks what she's doing. Flower tells her that she's the garden and to save herself.
In "Let's Raid The Warehouse", when Leafy is left with an awkward silence after trying to make conversation with the other receivers, Flower decides to answer back, saying her day is alright which makes Leafy happy.
In "The Game Has Changed", Leafy tags along with Flower to her store to get decorations. When Flower tells Leafy to go make her party, Leafy tells her there isn't enough time to make her party, and instead helps Flower with her party. Flower tells Leafy she'll give her the extra immunity if she wins. Leafy compliments Flower's party when they finish decorating.
In "Uprooting Everything", Leafy invites Flower to the newbie alliance, which she happily accepts.
In "B.F.B. = Back From Beginning", Flower tells Leafy that Four and X being so willy-nilly with the co-co-host is making her nervous. Leafy asks why and Flower explains that she vaguely remembers someone very powerful saying that three hosts is a sign of the competition falling apart. Leafy agrees with Flower as she brings up how they keep moving to new areas and the Profily fiasco. When they are both in the bottom two to be eliminated, Leafy asks how this could happen to them.
In "SOS (Save Our Show)", Leafy is the only one who is concerned for Flower when she gets showered with bugs on stage. When Flower is hesitant to give up her 50,000 dollars because of it being her dream to open a store, Leafy points out that it's also technically a dream of hers to get to the end of a BFDI season and urges her to give her money since she's so close, saying not to be selfish. Leafy then thanks Flower and Gelatin for saving the show.
In "Chapter Complete", Leafy votes for Flower to win because she's a plant, as Flower did the same last season, Flower thanks her and refers to her as "Plant Buddy". Leafy chases after Purple Face, initially to get the BFDI back to Flower. She's also the first to notice Flower never left the dangling bus. At the end of the episode, Leafy and Firey wave goodbye to her as they sail off to find their own Dream Island. Leafy congratulates her for winning and says that she deserves it.
In "The Glistening", Leafy asks if Flower minds jumping, since she just stands there doing nothing.
In "Insectophobe's Nightmare 2", Leafy apologizes to Flower on Bubble's behalf, she says that's adequate
In "The Hidden Contestant", when Flower calls it preposterous for Profily to join in the final 6, Leafy asks her if she rejoined in the final 6 in BFDI, which makes her change her mind. Later, as she rises with Profily, Flower nervously greets Leafy and Lollipop, when they are both shown to be near the BRB, as potential obstacles for her.
In "Uprooting Everything", Leafy and Flower notice a strange noise. Leafy asks what she thinks it is and Flower says it's probably nothing.
Episodes suggesting a conflict
In "Take the Plunge: Part 1", Flower pushed Leafy off the balance beam so she could have more space. Pin and Leafy attempt to push the "Evil Flower" into the water, but Flower simply kicks them away.
In "Take the Plunge: Part 2", Leafy has an uneasy expression on her face when Tennis Ball suggests that Flower should join their team.
In "Sweet Tooth", Flower is unsure what score to give Leafy's cake, so she spins a small wheel which lands on 10. She gives Leafy a zero regardless, to Leafy's confusion.
In "Power of Three", when Leafy's team opens a safe with a flower, Leafy says "Oh, I don't like Flower, she's mean" while flash backing to when Flower pushed her off the balance beam.
In "Don't Pierce My Flesh", when the Announcer is killed, Leafy says she thinks it means that everyone still in the game wins Dream Island. Flower disagrees and says only she wins Dream Island. When Flower is safe from elimination she tries to high-five Leafy. Leafy says "Uh, no thanks" so Flower hits her. In the volcano, Leafy accidentally pushes Flower into the magma when she was only trying to encourage her.
In "Hurtful!", Flower always asked Leafy who should go next in the furnace. After Firey, Ice Cube, and Bubble have gone in, Leafy suggests that Flower should have to jump in eventually. Flower pushes Leafy off the bridge at the start of the contest. Leafy is upset when she hears that Bubble would rather be with Flower instead of her, though this is because Flower says she would. Leafy becomes even more upset and shocked when she hears that Bubble helped Flower over the rock wall. Leafy then ends her friendship with Bubble, and Flower casually pushes Leafy aside into the magma.
In "Return of the Hang Glider", Flower doesn't want Leafy, Firey, or Bubble to win because they all have killed her. Later, she throws the Leafy Recovery Center in the incinerator.
In "Take the Tower", Flower attempts to mock the Four-Colored Team's name, which is meant with a blank expression from Leafy.
In "Who Stole Donut's Diary?", Flower tells Leafy to insult Taco on her behalf. Leafy refuses to listen a second time, saying that they should be nice to her.
In "The Tweested Temple", Leafy says no when Flower asks everyone if they want her sweaters.
In "Chapter Complete", Flower, Leafy, and the others were fighing over the BFDI.