Well, funny you should say that because I was doing a bit of digging on Plumarielle, Runie's highly suspected PL (I would say it's safe to say they are the same person). Initially I thought finding anything about her would be a nightmare considering how briefly was she was around for, but someone out there actually backed up basically everything she ever did from pre-debut to graduation, including all her media posts to twitter and tumblr, her streams, her shorts, everything.
archive.org
Some quick things I noted down:
-lists her skills off as singing, voice acting, drawing, writing (poetry, song lyrics, skits and comics - she particularly enjoys doing 4koma) and dancing (claims to be able to sing and dance at the same time)
-did all the lyrics for her own original song
-seems to speak an intermediate to advanced level of Japanese, said she wanted to do study streams and also do JP timeslot streams which were 'quite different' from her own time zone
-barely plays video games, expect lots of zatsu content, karaoke, sperging about anime/manga and some ASMR
-anime/manga nerd, favorites include Golden Kamuy, Buraiden Gai and One Piece (which she read the entirety of last winter)
-is a pescatarian
-when thinking about what a cool alias for herself could be, she suggested 'the purple smoke', which is curiously the exact same alias now being used by Muyu
-might be friends with Nova Aokami? Did art for her, Nova was in her stream chat and was one of the first people Runie followed outside of PC
On why she quit NexStage, no official reason was ever given but the rrats over on /corpo/ seem to suggest what was fairly obvious, after NexStage suffered a fairly bad start and her getting locked in to PC she didn't see a reason to stick around so bailed out early. The guy who left with her apparently didn't have much interest in being a vtuber to begin with and saw her leaving as a good opportunity to leave as well. Different posts also seem to suggest there may have been some animosity towards her for her actions, particularly from staff and also the other guy who quit.