For as far back as Alastair can remember, his older brother Alexander had been the only family he knew. According to Alexander, their father left their mother shortly after she found out that she was pregnant for a second time, and their mother died giving birth to Alastair. Without any money or means of supporting themselves, Alexander began begging in the streets of Korvosa for gold to support himself and Alastair.
As the two grew older, their skill in the streets grew. They found that they could work together to trick people into giving them money, or cause a distraction so that their targets could be more easily pickpocketed. They didn't have much, but they were able to live better than they had when Alexander was begging.
Alexander was all Alastair had in his life, and he idolized his older brother. Alexander taught him how to sneak around a corner without being heard, how to change his hair and clothes to make him seem like someone else, and how to wield, but more importantly conceal, a blade or ten on his person.
One day, Alastair returned to he and Alexander's alleyway after scrounging around for food and found that his brother was not there. Alexander did not return at all that night, nor the next day. Alastair was heartbroken, and searched the city for his brother. Listening to the gossip on the streets, Alastair discovered that his brother had been accused of murder by a local fisherman, and had been arrested.
Alastair was sure that his brother could not possibly be guilty, and went to see this fisherman. He was able to trick the fisherman into revealing that he had been intimidated into lying and planting the murder weapon on Alexander. He gave the information to the city guard, and Alexander was released, but he was never the same. He relied on Alastair for everything, but still didn't seem to have the will to live anymore. Alastair's brother died soon afterward, his spirit destroyed by the murder charges.
Alastair was crushed, his only family, his only friend, his whole world now gone. But he had one thing that gave him motivation to go on—the name of the man behind the actual murder and the one who had set up his brother. That man was Gaedren Lamm, and Alastair would not rest until the man who had taken away everything from him was brought to justice.