Alphonse was born into a minor noble house, the eldest child of the Veritas family. He had an easy childhood, doted upon by his parents and other family.
In his teens, when his Celestial nature was discovered, his life changed a bit.
His parents still loved him, and so did everyone else, of course. They loved him a bit TOO much in fact, and while he was too polite to say it, he felt a bit smothered.
He did his duty for a number of years, resigned to the fact that he was the only one who could keep up the family estate, and keep up the line.
However in his 30's something surprising happened. His mother had another child.
He began to hope at that point that he could have something more. He stuck around a bit longer (10 years or so), to make sure his new brother would be loved and cared for as he was, and would have a normal childhood. Satisfied that he was, he gave his parents a notice. That he was leaving, to go seek something MORE.
For the first time in his life, they objected to something he had said. They needed him, they said, to carry on the family name. He pointed out that they now had another child, and firmly said that he was leaving. He'd come back to visit, of course, but he had to seek his own path.
Puzzled (he'd had everything he ever wanted, after all!), but resigned, his parents acquiesced.
The next morning, he was on the road, traveling, learning new things, finally content with his life.
A bit of time passed that way, a few years at most, before he met up with a man in a forest between his home and Cheliax. The two sat, and talked, and soon became fast friends. The man explained that he was a Ranger, a walker of the wilderness. Alphonse was fascinated by the man's life, drawn to the freedom of it like nothing ever before.
When he left the next morning, continuing on his travels, he determined that he wanted that life for himself. Self sufficiency and adventure, his two favorite things.
He already had combat training, and he'd learned how to take care of himself pretty well in the wilderness, but he pushed himself farther, testing himself by cutting off from all civilization for long periods of time, surviving only on his own skill.
He never did meet up with the man again, but he had a profound impact on Alphonse' life, more than anyone else he'd ever known.
