Warning!

My idea is that they are divide into two "teams" (gangs?): the yellow, orange, and green ones are themed after nostalgic shows and comics - yellow and orange are combined with the cowboy show tapes and super hero comics respectively, and green is inspired by the fan theory about "apple girlington," Toby Fox's joke Touhou OC. They are all Very Anime and do not have a singular braincell between them. Cyan, blue, and purple have a less coherent theme going on tbh, they're mainly more mysterious and elegant - except for purple, who isn't very good at it.

Orange and cyan are the leaders of their respective teams, and are also siblings. I imagine that blue and yellow have some kind of Toxic Yuri Situationship going on, and green and purple probably have a much cuter and more wholesome little thing going on with each other as well. They all use any pronouns, as they are flowers and therefore neither male nor female, though other darkeners in their dark world tend to default to feminine descriptors for all except orange, who is generally seen as masculine, and yellow, who doesn't really lean strongly one way or another.

The general idea behind their story would be that the two teams used to be one large team, but after Asgore and Toriel divorced, they split off into rival gangs due to some siding with Toriel and some siding with Asgore when it came to how they reacted to Dess' disappearance. Yellow, orange, and green, representing Justice, Kindness, and Bravery, sympathize with Asgore and his desire to get to the bottom of what happened and try to set everything right and back to how it should be - this is because they are all more active traits, as well as their close proximity to items associated with nostalgia. Cyan, blue, and purple, representing Patience, Integrity, and Perseverance, sympathize with Toriel's desire to just accept what has happened and move on - they are all more passive traits, and rest farther from Asgore's living space. These differences caused the flowers to split into their two factions, who are now in constant battle to win over the favor of the rest of the dark world denizens.

I haven't designed a darkener for the golden flower, but I would imagine they would be involved in the resolution of this conflict, as a sort of "child of divorce" in a way, where they do not side with either Dreemurr and maybe care more about what Kris feels? Idk, there's a reason I'm not the one making this game lol.