The first moment in Roy's life we're able to witness happens right after he's enrolled the military. The Roy we see -- still not a National Alchemist, not even a flame alchemy user -- is a young man, an idealist determined to help his country and the people who live in it. He's been taught alchemy by a man who happens to be Riza Hawkeye's father and who is unnamed as of yet. The nature and length of the relationship with both his teacher and his daughter at that point, is left for especulation for now.

At that moment, Roy view the military as something he thought could make him useful for his country. We can see he was blinded by the military's promises, which at that point was already being ruled by Fuhrer King Bradley. Roy's eyes shone reflecting the bright future he thought he could help in obtaining, but instead found himself falling in a trap due to his naivety -- just as many other people.

     

His teacher, in fact, passed away before he could see Roy's "mistake" (although he predicted it) and even before he could present Roy with all his alchemy knowledge. However, the secret of Flame Alchemy lied carved in the skin of her daughter, and he relied on her the decision of sharing it with Roy or not.

Roy, unaware fo this, offered a helping hand to Hawkeye during her father's funeral, in case she may need it. He had decided to work in the military for life, for the sake of the dream he confessed to her at that moment. It was his wish to work for the people and try to protect everyone with his hands, even if his teacher's ultimate knowledge was now out of reach for him.

Only it really wasn't. Hawkeye believed in Roy's sincere words and uncovered her father's secret to him, in hope he'd make good use of it. But history had a cruel turn of events in mind none of them could have predicted.