Ruby seems to be the only character who is actively giving Flower a chance to be her friend, seeing as how almost everyone else dislikes Flower because of how mean-spirited she used to be.
Episodes suggesting a friendship
In "Zeeky Boogy Doog", Ruby revives Flower back from the dead, much to Pencil, Match, and Gelatin's dismay.
In "Getting Teardrop to Talk", Ruby calls Flower beautiful, which makes Flower want Ruby to be on her team later in the episode.
In "Lick Your Way to Freedom", Flower can be seen smiling at Ruby when she gets her cake.
In "Fortunate Ben", Flower pulls Ruby away from her game with Match because she was the only one who ever called her beautiful and she wants Ruby to convince her friends that she's pretty. Ruby then helps Flower look more beautiful by criticizing every position and movement she makes. Ruby also states that she hates the game "Flower Power" because Flower always wins, implying they've played the game together before.
In "What Do You Think of Roleplay?", Flower and Ruby are both seen sitting at a bench, angrily eyeing Foldy, implying that Flower told Ruby about how Foldy stopped her from winning in "Get to the Top in 500 Steps". They both sit together during Cake at Stake and later try to figure out who the impostor on their team is.