Today’s Strong Female is one of a pair. She is one half of Warrior Girl and Princess Boy, the idea developed by Mr. Thomas Sanders. 
Why is she strong?
Well, the first thing to note is that she’s a battle-hardened warrior with years of experience under her belt. She knows what to do and how to get the job done.
Given that the idea was just developed by Mr. Sanders within the past two months, there isn’t much to go on on backstory, so I’ll develop a quick outline here. The girl and boy are older here, like mid twenties. 
“Iona of the Azure Staff was tired of doing bounty hunting and decided to quit. Quitting the hunter’s isn’t easy. While not a particularly tight-knit group like the assassins, they did have a long-standing policy of…removing former members. Taking stock of the situation and her location in the country, she decided to look for work in the city of Verdant Spire.*
*She…would rather not go into the events that transpired between her decision to quit and her arrival in the city right now. Good reader, wait for her to recover please and respect her decision.
While she was taking in the sights, she wasn’t looking where she was going and collided with someone.
That someone looked up at her, collecting himself off the ground very quickly. She took a good look at him with a healthy dose of skepticism: tall, muscly, curly-toed boots, tiara, frying pan…
Wait, tiara? That was unexpected.
He brushed off his skirts quickly, using a basic descuffing spell to remove the mud stains. He then turned to her and spoke. `Hey, nice staff. You’re new here, aren’t you? Want someone to show you around?’
`Yes. The city map,’ Iona said.
`Ouch. Again,’ the man said. `Well you’re not going to find much the way you’re going, though.’
`And why is that?’ Iona responded a little coldly.
`Because what you are looking for,’ he said, `cannot be found on the main maps of the city. Come over here a second.’
Curiosity piqued, Iona followed the…strangely clad man over to a rather nondescript wall in the corner of the market. She wasn’t sure what was going to happen, but she didn’t really feel threatened either. Besides, it was rare to find someone who wasn’t intimidated by her fighter’s frame. Or her reputation.
The man brandished his frying pan with a flourish and tapped some bricks in a percussive manner. They slid back, showing a dark passage. `This way please. Mind the rats!’ he said. `Awful things, keep attacking my fancy shoes they do.’ He strode boldly into the dark passage, beckoning her to follow.
She paused at the doorway. Years of experience had taught her to be cautious in dark alleyways, much less those with strange men beckoning her down them. Yet she sensed nothing untoward. Anything that tried to attack her in the darkness would be taught quite a swift lesson indeed. She stepped over the threshold and followed him, the entrance sliding back into place behind her.
The corridor widened as they walked down it, until it ended in a door. A door with a red star upon it. At the door he paused and turned. `Here we are! Behind this door–‘ he said opening it swiftly, `–is a future for you.’
`Future?’ Iona asked. She stepped through and saw–
People ran about in one corner trying to organize documents into a coherent whole. In another part a large chalkboard was installed on the floor, people sketching out ideas and debating with each other over the quality of their theories. Iona could hear the noises of a training room off one of the side corridors. In the center towards the back was a large desk covered with paperwork, pens, and the odd desk artifact. Light streamed in from a combination of magical lanterns and the odd sunlight in the roof.
A door in the side opened and a page ran up saying, `Princess! We’ve got that file for you on Iona of the Azure Spear you wanted! Looks like you’ve got things in hand already.’
`Splendid work! Looks like you HWARK–‘ Iona had pinned this strange man against the wall by the neck with her staff, her gaze steady, but deadly.
`You will tell me how you know my name.’ She said it flatly, without dropping into anger, but there was the tiniest hint of menace.
`HURGHKLEhangononemoment,’ he gasped under the stout staff. `ifyouwantmetotalkshouldn’tibeabletobreathe?’
Iona released the pressure slightly. Just enough. `Use it wisely.’
`ThankGASPyou. Yes, as I said, a future. From this room I know all that is going on in the city. Both in the official channels and the…unofficial ones. We knew that one of the bounty hunters of the northeast region of the country had had a spat with the local hunter’s guild and decided to quit. Until you got within 5 miles of the city I hadn’t known who it was, but really I spotted you coming a mile awayHUWARKI kind of need my goatee.’ said the man, feeling rather uncomfortable under Iona’s intimidating gaze and more intimidating staff. He brushed the mussed hairs of said goatee back into place.
`I don’t like being tricked. What does this organization have to do with me? And why did that one call you princess?’ Asked Iona, perplexed.
`What trickery did I do? I asked you to come and you followed. By the way you missed three of the crossbow guards in the walls on the way in,’ he smirked in a rather gotcha way.
Iona mentally thought back to the recent events. She HAD thought she’d seen the glint of light on a metal helmet, but had not given it much thought. She’d been running hard the past few weeks and hadn’t had much time to do much more than eat, sleep, and survive. Kicking herself mentally for missing such an obvious tell, she refocused on the man.
`CONTINUING,’ said the man,`by the time you got within five miles of the city we were certain it was you. This isn’t the only office I manage. There are branches throughout my kingdom.’ He gently placed some fingers on her staff to lower it a bit from his neck. `We had heard of your skills, and your situation, and decided that the skills you developed should not go to waste. I brought you here, to the Royal Investigation Chamber of the of Third Princess of Verdant Spire. To MY Royal Investigation Chamber. Lovely, isn’t it?’ He gestured grandly around the hall.
`Princess? Of Verdant Spire?’ Iona was now thoroughly confused. `Then that means that you are–‘
`Yes!’ He gestured grandly. `I am Felix Alba Kildare, Third Princess of the realm of Spira and lead investigator of the city of Verdant Spire.’ The aide whom had brought the dossier made little trumpeting noises after the announcement.
`Third?’ Iona asked.
`Old tradition. There’s been three girls born in every generation of the royal family time out of mind. Until mine. My parents decided to keep the appearances of the tradition going at least. So here I am, a princess.’ Felix said. `There’s not a lot for the third princess to do. My eldest sister Ophelia is heir to the throne, and my second sister is ambassador to the sea kingdom of Aquaria to the east. So, when I came of age, I decided to give back to my city in a different way. I’d been interested in the welfare of my city from more of a grassroots perspective anyway.’
She couldn’t believe her ears. `I’ve been tricked by a PRINCESS?!’ It was beyond her experience. Confusion and incredulity covered her face.
A glow. Green magic runes etched themselves on an iron surface. CLANG.
The staff was suddenly knocked away from her hands. He held the magic frying pan forward from him pointing to her. His tiara and magic runes on his frying pan and clothes glowed. His eyes glinted hard, determined, but not cruel.
`Do not assume, warrior, that princess means weak. Or that my clothes make me any less of a person. You of all people,’ Felix gently admonished, `should be aware of the damage a careless assumption can do.’
Iona was shocked and humbled. She had messed up very badly. That wasn’t like her.
Then again, this whole situation wasn’t like her. Following people to strange areas, missing obvious tells, her weapon getting knocked away from her and she still alive…it was very odd.
`I’m sorry. It’s…been a long week.’ Iona said, running her hands over her mohawk. `I’m big enough to own my mistakes. I won’t make that assumption again. But, what would you have me do, Third Princess?’
`Please,’ Felix said lowering his frying pan and smiling, `Felix will do fine. I don’t care for titles really. Oh yes! The offer. We would like to hire you as a protector of sorts for this city. I do a lot of footwork, as do my clerks and footmen, but we can’t cover all the city and most of these folks are trained in stealth, not fighting. I, er that is we, need you to accompany me on my trips around the city in my investigations.’
`I just got out of an organization that was entirely fighting, and you want to throw me back in? Who is making the assumption now?’ Iona countered.
`Point made. The difference is that while your former…colleagues did train you in all types of fighting, they did not give you the one thing you need most,” Felix said. He lifted her staff and handed it back to her.
`And what is that?’ Iona asked, taking the staff back.
`A stable place to come back to. One that won’t end up with a knife from the ceiling, or wondering if your neighbor down the hall is going to aim a crossbow at you one day, or your boss’s uncle deciding to turn you into a newt just for kicks. A, well, a home for lack of a better word,’ Felix said. He grandly gestured again at the space around them, filled with people clearly satisfied with their work and what they were doing. `We start you out on a trial period of three months, open to further employment afterwards. You’ll learn the streets, perhaps teach our people a few moves. Bed and board provided.’ He then twirled and posed, hands open. `What do you say?’
Iona looked around, seeing a form of stability that she hadn’t had for a long, long time. She couldn’t remember the last time that HAD happened, actually. She said `I accept your offer, Prin-Felix.’ She extended a hand.
`Excellent. Welcome to my world.’ He extended his hand and they shook on it.
`So what happens noqwoooooooorl’ Her stomach growled loudly, interrupting any further conversation.
Felix laughed `As it should be, Iona! (Can I call you Iona? Kthx.) There’s a room prepared for you down the hall. First we should get you some food. There’s some really great samosas today…’ He led her down to the kitchen, for the first of many conversations over good food and with good company.”
Keep it civil people.
Update: I found the commentary to the original post! It isn’t the original quite, and it has a different backstory than the one I developed here, but it’s the same idea.
 I couldn’t find the original tumblr post on Mr. Sanders’ website, so I just linked to the tumblr as a whole.
 This is just my interpretation. There are many, many others. Good ideas out there.