A very interesting question, and one I don't really have a definite answer to!
Most of the time when I create characters, I have many influences including songs and other works, Nyrané being no exception, but then once they get established they divert strongly from the original sources being fitting descriptors for them.
The only persistent tie-through for music that fits Nyrané at different times of development were tones of either melancholy or aggression, fitting her backstory and characterization as a DnD character, a once-diplomat that covers up her physical weakness with a front of reckless confidence and brilliant arcane power.
Originally, the song that served as Nyrané's 'theme' while just an idea boiling around in my head was a touhou remix I found from like 10 years ago (( https://www.youtube.com/watch?v=i5TPJFcFP70&list=PLMqSqSrP-AhYoz6Ntv8WCqhWJ-6AZymWC )) but that doesn't really work for her now that her character is a mixture of mournful reflection and getting drunk with power
Later in her early development, I kept an english cover of Phony (( https://www.youtube.com/watch?v=YHc5mNQQyNo&list=PLMqSqSrP-AhYoz6Ntv8WCqhWJ-6AZymWC&index=80 )) as a theme, but again, that doesn't fit her current form, it's too sad and she's getting away from her backstory well enough (still could fit a younger version of her, back when she was still a Diplomat proper)
Somewhere between 2021-2022, about when Nyrané lost her more cheerleader-y outfit under the coat and adopted the design that has remained mostly unchanged since then to now, I decided that any song with lyrics would be harder to use to represent her as I hadn't found anything that fully clicked, and would be better to search for something that just sorta fit the vibes of her, which was even more of a challenge. What I'd truly like is something like guilty gear music, a ballad with backing of loud instrumentation to represent her efforts to shield her emotions beneath bravado and composure, but there wasn't any song I found that really fit that category.
I went through a lot of instrumentals and covers of songs I enjoyed, but I couldn't really find something that represented her as a character, at least not outside of accumulating a playlist of like 20 songs which I was too lazy to do.
As of right now, I've been using the Thunder Serpent Narwa's theme from monster hunter (( https://www.youtube.com/watch?v=5klQrRTDtRs&list=PLMqSqSrP-AhYoz6Ntv8WCqhWJ-6AZymWC&index=342 )) as a sort of 'dramatic non-combat' music for her, the type of thing that would play during pivotal character development moments but not during the heat of battle, as that would probably have something more hectic or metal guitar-using.
At one point I was using Bury The Light from devil may cry as her solo battle theme but thats far too edgy for her now. Still looking for something fitting for her idle life and proper combat themes. Shoutout to this Vyke elden ring inspired music (( https://www.youtube.com/watch?v=uyAAbMlfJ3Q&list=PLMqSqSrP-AhYoz6Ntv8WCqhWJ-6AZymWC&index=343 )) for being the closest contender I have in my head right now for a group battle theme for her, something slow and dramatic would fit for her strategy as a tactician and commander of allies compared to her in a 1v1 fight where she throws all caution and mediation to the wind.
(You know a character is fun to think about when I need to come up with like 5 different songs for different states of her, since she behaves so differently depending on what all is happening around her.)