Source Info: Avatar:
Air NomadsAirbendingSky BisonBaguazhangHsing_YuGliderEastern Air TempleNorthern Air Temple Casting
Alphonse - Airbender ; Avatar
Edward - Brother to Alphonse ; Earthbender
whatsalchemyWinry - Airbender ; False Avatar
whatsautomailLing - Prince of Fire Nation ; Firebender
whatsxingMei - Psycho Sister to Ling ; Firebender
Tentative Background:Like almost all Air Nomads, Winry was raised in one of the four communes, one of the four temples. She was placed in the Eastern Air Temple, being one of those where female monks are raised (the other, the western air temple). She never knew her parents, but that was never something that bothered her since that was the case for all air nomads.
When she was two, the Elder Pinako had a vision that told that that Winry was needed at the Northern Air Temple, and so she was sent there and raised with two other boys, Edward and Alphonse. They too were breaking tradition for a bit, for they were known to be brothers, and of different elements as well; Edward was an Earthbender. The three of them had their share of problems, but were always together.
The Elder Pinako would visit Winry about twice a year, which is not much, but they were incredibly close nonetheless. She was a great teacher and confidant and someone Winry had dedicated herself to following her steps. Her utter faith and devotion to Pinako caused her to throw herself into her training and beliefs fully, making her master the element and earn her arrows at an incredibly young age. She is also rather skilled in the rare subform called Soundbending.
Since she was raised in a temple that housed only boys, and her only contact with another female was Pinako Winry's view of gender is rather skewed. She doesn't even realize that she refers to herself as a boy, or even exactly what it means that she does. It's not that she actively tries to be manly or convince others that she is, not even that she is naive, she just simply doesn't register genders.
When she and Edward were thirteen, and Alphonse twelve(?), Alphonse was revealed to be the Avatar. Typically it is upon their sixteenth birthday that the Avatar is told, but the Fire Nation had started to show signs of aggression and the Elders realized that Alphonse would be needed soon to ensure the peace of the world.
Unfortunately the Fire Nation launched a surprise attack upon all the Air Temples, knowing that the next Avatar would be born to the Air Nomads. Edward, Alphonse, and Winry managed to escape on Winry's flying bison, Den. Before they did Pinako cemented the importance of protecting the Avatar to Winry, and it has become her entire life. As they were escaping, they got caught up in a storm near the south pole and nearly drowned, Alphonse, however managed to save them by encasing them in an iceberg. They were trapped inside for 100 years, until released by some stray villagers from the nearby water tribe.
Since learning about the situation of the world, the three have decided to travel to gain him a Water and Fire teacher. Knowing the importance of the Avatar to the world, for his safety Winry masquerades as the Avatar.