You're a girl?
Woman. My name is Mulan.

Hers was not a traditional upbringing.
She took up the sword not from her own desire, but from the need of a family with no son and an aging patriarch to defend itself. Her land was in chaos, at war with invaders since before she was born. She assumed the war would continue long after her death.
She was wrong.
She grew up surrounded by fear, taking a boy's role in girl's clothes to replace the brother she never had. It was only natural that when she became a woman, she took up a man's place in the army.
In another life she might have hidden her sex and enlisted in her father's place. In another life she might have become a legend, saved her country. In this life she did not hide her long hair unless she tied it up to keep it from her eyes. In this life her father went to war alongside her and died in her first battle.

Love is sacrifice.

The arrow had been meant for her: she knew it like she knew her own name or the name of the man who had pulled her out of the path of a second arrow when she sobbed over her father's body.
Her father taught her how to fight; Li Shang taught her how to survive in a war, and, eventually, how to lead soldiers into battle. He'd learned these lessons from his own father. A true commander, he'd said, led by loyalty and example, not by fear and cruelty. A true commander's followers would go to the ends of the earth if so ordered. They would die, if so ordered. She wasn't sure if she believed that, but she knew that she would do anything for him. He knew it too.
The war raged on, and the only joy she found was in fighting every battle with Shang at her back, trusting and thrusting her sword as the two best men she knew had taught her. She barely noticed the tide turning against them; it happened slowly, one inch of ground lost each day, pushing them to the border of another kingdom.
When the lines broke for the last time she fled from the battlefield, ready to regroup and fight another day. She didn't realize that the war was over until they had been chased to a rickety bridge, Shang's hand in hers as they hung from it with enemies closing in on all sides.
I love you, he'd said, and then let go.
She had no memories of how she'd escaped. She only remembered gazing into an unfamiliar, concerned face as she lay on the ground, wet with the night's rain, her sword unsheathed beside her.
Before she knew it she was caught up in Philip's quest to find his princess. She called him by the wrong name more than once in the heat of battle - he never complained and she never apologized. The twenty-eight years spent frozen didn't stop the camaraderie building up between them. He made her smile again, though not as she'd smiled for Shang. She had learned what love did to your heart.

I know love when I see it.
You're wrong.

She took an instant dislike to Philip's princess and did not hide it: perhaps that was why Aurora had accused her of what she'd been refusing to think about. As she followed Philip's tracks, carefully keeping her thoughts from the man who had taught her to read the signs in the woods, she wondered if it could be true. Love was sacrifice, after all, and she knew what she intended to do.
She could easily have knocked him over and taken the mark herself, but she hadn't, and she didn't know why at first. But, as she put an arm around a grieving Aurora, she thought that maybe she'd known that, somehow, it was what he would have wanted. She had to live on, take care of Aurora, find her mother and save the land.
If she wasn't sure which man she was thinking of at that moment, she would never have admitted it to herself.

A/N: I wrote this story the day after seeing the season premiere. I realize this will probably become very non-canon very quickly, but until the show comes up with something (better) this is my headcanon for Mulan's backstory, playing off the Disney version (including the sequel, though I still hold that sequel to be non-canon in the Disney Mulan universe). Thus ends the super-parenthetical author's note.