Hello! You wanted an ask about Fi? Here's your free ticket to spill everything you have about her! Tell me!!! <3
yesss lemme ramble!! tagging @daughter-of-melpomene for this too, since i already talked about fi in the discord.
okay, so like i said in fi’s intro post, she is a royal bitch. literally.
princess fiametta topazia cherubini, the second-born daughter and the 'spare heir' if you listen to the whispers around her family's kingdom. her older sister, the crown princess dianora violente, is a picture perfect princess and has been prepped to take over as queen since she was a child. fi, meanwhile, has always had a less-tight leash when it came to her parents.
fi's life was all garden parties and sunshine and not attending her lessons, even at her parents' behest; she was always kind of performing, whether it be the rebellious princess or the garden party snob or whatever role was necessary to fit in with her peers. since she was never expected to have to take over a ruling role, her parents kind of dropped the ball with her while they focused on her older sister. so she was kind of always just doing whatever the hell she wanted, since nobody really seemed to care anyway. she's very much the embodiment of her name, 'fiametta' meaning 'little fiery one'.
she was childhood friends with kaya, since their parents were friends and fi's parents often paid kaya's for ships. fi, of course, comes to celebrate kaya's 18th birthday where she first meets the straw hats. she's known of usopp for a while, but they're not close and if fi was a little bit in love with kaya and thus a little bit jealous of usopp, that's nobody's business. when usopp brings the straw hats to kaya's birthday dinner, fi does admittedly refer to them as 'riffraff' - though not in front of them - even before she finds out that they're actually real pirates.
kuro wanted to get fi to leave before nightfall, because even he knows that he can't risk killing an actual princess in the same way he can kill a bunch of pirates and a sick girl, but fi insists on staying overnight. that night is her first taste of pirate excitement, even if it is terrifying.
a few weeks after she returns home, her parents inform her of a marriage proposal they've secured for her, one that will join two 'fighting-but-not-yet-warring' families. they had refused to offer their crown princess' hand in marriage, unwilling to allow the other family's son to become king of their lands, so fi was offered instead since she is already of age. fi takes it for what it is, since there's little she can do. she's kind of always known it would be what was expected of her, that she would be some bargaining chip in her parents' politics. she's just pleased that her betrothed - prince hyacinthe - is handsome.
so, she's sent off on a royal ship with a couple of her handmaids and a crew of her father's kingsmen to go get married. halfway between her land and her betrothed's, their ship is attacked by pirates and fi is captured. it's the first time she's ever been offended by being called 'the spare', and the first time she actually realises she is 'worth less' than her sister. a ransom is sent out for the princess' 'safe return home', fi thinks it's a paltry amount to demand for her life and gets even more offended.
the straw hats discover the ransom and go to rescue her (much to nami and zoro's annoyance since fi isn't on the best of terms with either of them). sanji, at this point, has joined the crew. the strawhats, of course, succeed in rescuing fi and head off to return her home. fi and sanji obviously flirt the entire time, but she also gets a chance to actually get to know luffy and usopp and the adventures they've had since kaya's birthday.
after getting home, fi insists that the straw hats stay and enjoy a reward for rescuing her. when she's finally left alone to her own thoughts, she realises how unhappy - and how underappreciated and ignored - she's been for years. so, days later, when the straw hats are preparing to leave, fi practically demands that they take her with them. after the initial bitchiness, she lets her facade down and actually has a moment of sincerity where she confesses how unhappy she's been, how she's never been more than just the overlooked 'spare heir', and that she doesn't even truly know who she is.
she's still a total priss for a long time even after joining the straw hats, but she eventually grows out of it.
i've been thinking of giving her a devil fruit that she stole from her family's treasury before leaving, but i haven't been able to work all the wrinkles out yet. i wanted to do something with fire, since her name does mean fire and it would suit her, but since there's already a devil fruit surrounding fire, i was thinking something more with sparks maybe? or candles? or bombs, i've been thinking of giving her bombs as a signature weapon.
bonus: crown princess dianora and prince hyacinthe!