Paleberry, Briartuft, Skykit, Rosegaze, and Goosewing are all sisters. It was mentioned in Rogue that Paleberry and Briartuft were also Finchstar's kits.
Skykit died of greencough as an apprentice.
Back before I wrote Exile, I tried to write Lost (or something similar) I only wrote a few paragraphs, and in it, Ashpaw was trained into the Dark Forest by her mysterious mother while her sister Russetpaw was blessed with dreams of StarClan. I forgot about this until much, much later, and so Russetpaw never actually existed.
The major plot points (to keep the story in order) for Lost and Exile are written in the same notebook.
When Larchfall says he'd like to repay Ashpoppy for being mean to her, the favor is repaid in Rogue when he helps attack the Allegiance cats in order for Ashpoppy to kill Breeze. She knew he would die in that battle, and she didn't care.
Finchstar's younger and arrogant side is explored in Lost, proven by him executing Sundusk without question. This is what gave Ashpoppy a nudge to kill him in Rogue and not feel remorse.
Finchstar did feel bad for killing Sundusk, though he was too scared to apologize to Ashpoppy. He tried to be nicer to Breeze, Runningleaf, and Redfire in order to make up.
Runningleaf was named after the race, Breeze after Hollybreeze (because Ashpoppy did feel bad for not choosing Hollybreeze over Ravenshade), and Redfire for his fur. Ash poppy's line "Well, if all three of my kits were named after dead warriors, it would feel a tad unoriginal," was a reference to Lionblaze's kits, who were all named after dead warriors.
Hollybreeze wasn't going to be a major character, she was simply going to die before Ashpoppy was apprenticed. However, when I realized she was a -breeze and so was Ashpoppy's kit, I knew she had to be important. To, you know, carry on the name and stuff.
The reason that Ashpoppy knew of the Allegiances was because of Pinestar. Pinestar's mother Whitemist was the son of Night, an Allegiance cat, as shown in Rogue. During their morning walks, Pinestar would pass down stories from Night to Ashpaw.
Finchstar never loved Pinestar back.
Sandhawk got his arrogance and abuse towards others form his mother, Applefern. Graymouse, his father, was deputy, which (in his mind) gave him the right to be cocky. By the time Graymouse died, he was the monster that Icefern and Sorrelbreeze knew. He was this way because he saw the way Applefern treated Ashpoppy and had no idea how to be a proper parent.
After Ashpoppy died, she most likely destroyed Ravenshade's spirit after realizing how much her mother ruined her life. She did train Sagepaw, in Exile, though most of it was just battle moves. Sagepaw got his cruelty from Brindlepaw, for the most part.
Ashpoppy feels horrible for her treatment of WindClan, but can never cross to StarClan due to her actions. She sometimes meets Sundusk and Hollybreeze at the border, and longs to see Breeze to beg for forgiveness.
Ashpoppy's biggest regret in life is choosing power over Breeze.
Part of the reason Ravenshade wanted Sundusk to die was because she feared he would become leader, not Ashpoppy, and she couldn't let Hollybreeze win.
Ashpoppy has killed only three cats directly: Applefern (accidentally), Finchstar, and Swallowfur. Breeze, the main protagonist of Rogue, has also killed three: Stormstripe, Oakstar, and Ashpoppy. Ravenshade, the overall antagonist, has only killed one cat, Hollybreeze, but she oversaw and planned the murders of Oakstar, Finchstar, Sundusk, Gorseheart, Swallowfur, Stormstripe, and Breeze, giving her the total kill score of seven cats.
When I was first coming up with ideas for Lost I was into Wicked (thanks Wolf), and I liked the idea of having two friends, both opposites, split apart for their own goods. While technically it wasn't for their own good, Hollybreeze and Ravenshade were loosely based off of the two main characters of the play.
Hollybreeze's personality is based off of Cleverpelt's OC of herself.
Only two cats call Ashpoppy 'Ash': Sundusk and Ravenshade. Which is odd, considering Ravenshade hated the nickname Rave. (However, she most likely despises it as it reminds her of the good times between her and Hollybreeze, and thinks Hollybreeze just uses it to mock her.)