Purely biological speaking, Usopp was, a woman.
Growing up though, Usopp had never felt like a girl, in her youngest days when her mother put her in a dress Usopp hated it, and she much preferred to run around in overalls, climb trees, get dirty, and laugh loudly while splashing in mud.
All-ready then, people would express deep surprise when Banchina told she was actually her daughter, not her son.
Then Usopp's mother had died and left Usopp alone, with no one to put Usopp in a dress, Usopp simply never wore one.
Often the villagers of Syrup would laugh at her, calling her out for being such a trouble making boy, and Usopp assumed that that was what she was.
The villagers whom knew of her true gender thought it was an amusing joke, and went along with it.. until it became so blurred that they actually forgot.
Usopp didn't mind though, she realised that as long as she was a boy, no one would trying to put her in a dress, and the lectures should would get about being clean would be way fewer. She avoided a lot of trouble that way.
And as Usopp was around the eleven, she viewed herself way more as a he than a she, what could she ever gain from being a she any-way? And what difference did it even make?
She lived alone, so there was no one she needed to please, she took care of herself, and preferred to work the more practical jobs, such as fixing roofs and doors, than girlie stuff. Usopp like to move around.
Unless she was sitting down to invent or be creative.
Then she formed the Usopp pirates, they called her the great Captain Usopp, bravest man of the sea, Usopp liked that!
She had decided it, she was a he now, it was much more convenient any-way!
And she would one day become a true brave warrior of the sea! Meet her father, the strong sharpshooter, become strong and great, as Usopp the brave warrior! What did Gender matter?
By the time the straw-hats came to the island, as Usopp had turned seventeen, he was so used to the part that there went zero thought into it upon his introduction to the crew, their first adventure together, and as he joined them.
He did how-ever.. manage to give Nami a brilliant shock as he on the second day at Merry, had wished to take a bath. And for the first time ever, in his entire life, realised the bathroom wasn't his own, and some-body could sneak in on him.
For the first time in his entire life, Usopp had experienced just a small taste of what it meant that he had a womans body, and didn't wish to just show it to the male members of the crew.. so he had tried to sneek into the womens bathroom, only to be caught in the act by Nami whom had nearly choked him..
Until the towel fell off and Usopp's little secret was revealed, making both Nami and Usopp deeply embarrassed.
And that had opened up a whole new world of problems for Usopp, things she had never even thought about when Nami asked him what he preferred, to be a man or a woman.. and in truth, Usopp had never thought about it, he had just been a boy because that was more convenient to him, there was nothing else in that!
Eventually it seemed though, that Nami had decided just to let it slide, let Usopp go in and out of the womens quarters as he wished, and call him a 'he'
And Usopp could relax again, not having to deal with any of these issues just yet, he could continue just being Usopp, the great liar and sniper, wanting to be a brave warrior of the sea.
Then he entered Usopp's life.. that man would be the root to all of Usopp's promise.
Usopp didn't know it at first, he had no clue. That that blond that served them at the barratie, would be the course of so much trouble!
In fact, as the blond cook started to swoon and dance over Nami, Usopp was secretly happy that no one knew she was a girl so she wouldn't have to bother with that kind of treatment.
Lord only knows how that crazy person would treat Usopp, a very un-feminin girl, if he knew.. Crazy Sanji.
And for a good while, Usopp was happy that he wasn't on the receiving end of Sanjis crazy antics.
Vivi joined them for a while, and got a shock very similar to Namis as Usopp had casually walked in on them early morning to borrow the bathroom, and it had been up to Nami to calmly explain things to Vivi.
Chopper, bless the sweet-heart, also got a surprise at Usopp's first physical exam.. at first he freaked out, but then after a talk with Nami, said to Usopp he understood.
Thankfully Robin expressed no surprise at all as Usopp entered the womens bathroom again after she had joined, in fact two seconds after Usopp had started the shower, Robin had entered and offered him a fresh lotion 'to moisture the skin after all of that heat from Alabasta.'
And from then on off, Robin acted as if nothing, nothing at all, was out of the ordinary, didn't even mention a thing.
But things had really started to become complicated, and Usopp realised there were just some-things, he or maybe even she.. had to figure out pretty soon, so it wouldn't become an unnecessary distraction later.
But it hadn't become just a little bit as complicated as it soon would be, Usopp wasn't entirely sure when it started happening, some-time doing their adventure in Skypia perhaps, or one of the rare occasions where he got to talk just normally with Sanji, because there were no girls around.
Usopp started to notice.. Sanji may put up a dumb chivalric act quite often, but actually he was really nice, strong, funny, generous, he really cared for other and.. He was incredible good looking!
Usopp had no idea what was going on! He started acting irrationally, snapping at Sanji or other people for no reason.
He felt frustrated, when Sanji started to sing his praise to Nami and Robin, Usopp started to feely really really frustrated that she wasn't included in this special attention! She might called herself a 'he' but she was a she wasn't she? Why couldn't se get special attention from Sanji!?
Usopp how-ever, decided to dismiss all of that as childish and some-thing that would eventually go in itself, Usopp had no energy to deal with any of that.
Then there was water seven, the most horrific experience in all of Usopp's life, she had felt so worthless, so lousy.
She couldn't even protect her brave ship! Couldn't even keep the lousy money safe, to safe their ship.
She let all of them down! Her best friend Luffy! Nami, Zoro, Chopper, Robin, Sanji.. ALL OF THEM!
Usopp had been so convinced they would be better off without her, all she had left to do, was to look after Merry. Brave brave Merry.
She was so ashamed that she couldn't even face the crew as herself, so she made up an alter ego, just so she could help safe Robin! Her trusted Nakama.
Usopp couldn't do it.. but Maybe Sogeking could be of just a little bit help..
And then, he had been there. Sanji had been there, looked Usopp seriously in the eyes as he spoke honestly. "I do the things you can't do, and you do the things I can't do." He told. "We can make it through this Usopp, but only because you are here. To do the things we can't do."
It was a wonder Usopp hadn't started to cry by then, she had wanted so badly to thrust herself into Sanjis arms and cry her heart out.
But she had to go on and fight, they needed her now! Sanjis words were just exactly what Usopp had needed to hear to fight on for what she believed in, just for a little longer.
To rejoin the crew had been joyous! For just a little while, it was like all of that pain from the last couple of weeks had turned into pure happiness.
How-ever, a little while was the key-word there.. Soon all those negative feelings that had developed beforehand came back to Usopp, the doubt, the self-loathing over being so weak and useless… and..
Hopelessly Usopp could only look at Sanji in hiding from the other side of the deck, the cook were so often on Usopp's mind, when Usopp slept, when Usopp worked and drew, Sanji always bugged her mind.
And for the first time ever, in Usopp's entire life.. she minded that people thought she was a boy! She wanted to be addressed as a woman! But.. how could she even begin to explain that to the male crew members? How could she explain herself, that they had all trusted her enough to let her rejoin, after the things that she did.. only to find out she had lied ever since the beginning!?
Hopelessly Usopp grabbed her head with her hands as she squinted her eyes. "Dammit." She hissed.
"Usopp are you all-right."
Usopp glanced up to where she saw Nami standing above her.
"I'm fine." Usopp muttered looking to the side, averting her eyes away from Nami.
"You don't look all-right." Nami told as she sat beside Usopp, up against the railing on the deck. "Is some-thing wrong."
"I told you I am fine." Usopp hissed turning her head away.
Next moment as certain cook came their way. "Nami-swaaaaan!" he sang. "Can I offer you a light refreshments, some tangerine juice in this heat?" he asked.
Annoyed Usopp looked at Sanji. "Only Nami?" she asked annoyed.
"What are you saying shitty sniper?" Sanji asked in a murmer, addressing Usopp as he addressed all males every-where. "You want one to? Made from Nami-swans precious tangerines."
"So what if I do!?" Usopp asked annoyed. "Isn't that just good manners, to offer every-one?"
"Tch." Sanji rolled his eyes. "It's ladies treatment, you guys can wait." He snorted.
"It's ladies treatment." Usopp mimicked Sanji in a extremely mocking tone, crossing both arms as she mocked Sanji.
"Oi, are you saying some-thing you shitty Sniper?" Sanji asked annoyed, lifting a foot, as if warning to kick Usopp.
Usopp looked unimpressed at Sanjis food. Usopp had been hit by Sanji before, but never kicked, hah! And if Sanji only knew then… He would turn into a complete idiot and stop treating Usopp like Usopp!
That thought alone ticked Usopp off as she hissed. "Why don't you go and mind your own business Sanji!?" she asked in a very angry tone.
"Excuse me?" Sanji asked deeply surprised.
"You heard me, I was talking to Nami and you came here and disturbed us." Usopp replied in a warning tone. "So back off."
Sanji lowered his foot before he shrugged. "Tch, so much for trying to be nice, some-one is cranky today." He stated turning around and walked away.
"Usopp that was uncalled for." Nami exclaimed. "That's not like you."
"I just didn't want to see his stupid face right now." Usopp muttered annoyed collecting her legs in her arms.
"Usopp what's wrong with you?" Nami asked. "I swear, ever since we left Water Seven, you have been acting differently!" she stated. "And why is it precisely Sanji you let all of your frustrations out on. There are more people on this ship to choose from, but you are only after Sanji, why?" she asked.
"Because he's an idiot." Usopp offered, turning her head away.
"Usopp that's no explanation." Nami muttered. "I mean sure I get annoyed at him, but when I do it's because he did some-thing." Then she turned to Usopp, and suddenly realised. "Usopp are you crying?"
"Huh?" Usopp asked in a blink, then lifted a hand to her eye, and wondering felt the wetness of a tear, which she lifted on her finger to look at, as she could feel another silent tear falling down. "Dammit!" Usopp hissed whisking away the tears.
"Usopp why are you crying?" Nami asked concerned looking at Usopp.
"I don't know!" Usopp exclaimed. "If just that stupid cook would leave me alone."
Namis eyes widenened. "Usopp.." she hesitated. "Are you having a crush on Sanji?"
"What!?" Usopp looked up at Nami. "No no! that's ridicules!" she hiccupped. "I mean.. I'm a guy for all that he and every-one else cares. And he only cares for pretty women, and I'm not.. I'm never going to be a pretty woman Nami!" she exclaimed and then reached for Nami. "Nami, I never cared about that stuff before, why is this happening to me?" she asked.
"Hey, it's all-right Usopp." Nami smiled lightly, padding Usopp on the back. "Though it is quite the mess you have gotten yourself into here." She admitted. "Why don't you just tell Sanji you are a woman, he is bound to be overjoyed."
"No I can't!" Usopp shook her head. "Nami how can I confess, I lied to them! To all of them!" she told. "I did some-thing horrible, I betrayed you and still you let me rejoin the crew, and then I have to confess I always lied."
"But Usopp." Nami exhaled. "You never lied, you just never corrected a mistake we all made." She exhaled. "And I assumed you just viewed yourself as a boy any-way, so it wasn't lying."
"I just view myself as Usopp, nothing else." Usopp admitted. "I never used to think about it, I didn't care."
Nami exhaled. "Trust me, no one will be mad if you tell them, it'll be fine, and you will feel a lot better to."
"I'm sorry, I can't." Usopp shook her head as she stood up. "I need to go, work.." she mumbled. "See ya Nami." She waved over her shoulder, leaving in the direction of the work-shop.
Soon Sanji came, carrying a tray with two tangerine juices on it. "Oi, where's Usopp?" Sanji asked looking around.
Nami exhaled. "Left for the workshop." She murmered.
Sanji sighed deeply. "Did you find out why he is so upset Nami-swan?" he finally asked.
"I did." Nami confirmed in a slight nod.
"And?" Sanji asked lifting an eye-brow.
"I'm sorry Sanji, it would be betraying Usopp's trust to tell." Nami muttered. "Usopp is the one whom has to deal with this." She just hoped that the sniper would deal with it soon..
"Well that's troublesome." Sanji sighed. "I must admit, I miss the old carefree Usopp, Water Seven really made a number on him huh?"
"Yeah.." Nami nodded in a sigh. "Yeah I guess so."