Knight comes from a family of smiths, in particular silversmiths. However, he showed little interest in his clan's prevailing occupation, and at age 16, headed out into the world as an adventurer. He visited many villages, but had little luck, financially speaking. Eventually he returned home, at the age of 25. He felt he had no choice but to go into the family business, but at the same time, felt he didn't deserve their help, considering he had left them. Besides which, he believed he was too old to start learning a trade. In despondence, he eventually left his clan's home and became a street rat. After awhile, he ended up joining one of the local gangs, who called themselves the Rabble-rousers. This was a name Knight never really cared for, as he believed they were misusing the term, though he never mentioned this to any of his fellow gangsters, as he already felt like an outsider among them, being older than any of the others, who were mostly teenagers. By the time they all retired from the gang, as was the natural way for those things at the time, he was not only the oldest member, but he became, among the even younger generation, the longest-standing member. The newcomers therefore thought he should be the new leader, a position which he immediately accepted. This new generation appreciated the stories he often told them of the adventures he'd had when he'd been their age, but he soon segued into telling Earth stories he'd read in his younger days. Mostly these were Märchen, fantasy stories of kings and knights and such, and his subordinates came to associate their leader with the knights from these stories, because his own name was Knight (a name his parents had given him because of their own fondness for such stories; it was they who had first given him books of Märchen when he was a child). Somehow, these stories of medieval Earth led to Knight changing the name of his gang to the Royal Rebels.
The Rabble-rousers had always been a fairly competent gang, though nothing really special. But the Royal Rebels developed a stronger sense of romance about their role in society, and began taking their work more seriously. They soon became the most effective and organized gang in First Village, and Knight began feeling respect for himself, something he hadn't felt for a long time. Then, in 899, at 39 years of age, he was approached by a mysterious woman in her mid-20s, named Amelia. (There is speculation about how they met, or whether in fact it was some time earlier than 899, but the truth is known only to the two of them.) At any rate, it was in 899 that she proposed forming an inter-village gang, which she called InterGang, and she wanted the Royal Rebels to be the first to join this new alliance. For some reason, Knight accepted her as the leader of this new gang, and he became the don of its First Village branch. He remains Amelia's most trusted don and one of her closest friends, though she seems to have few truly close friends.
When the surname law was passed in 904, Knight chose the name "Errant," apparently as a pun on his first name. It is believed that he chose not to take the same name as his clan, because in spite of the respect he now felt for his accomplishments, he still believed himself unworthy of his family, due to his having turned to a life of crime, and he didn't want them to suffer an association with himself. Some have said that the term "knight errant" doesn't really apply to someone who never leaves his home and never takes on any special quests, but Knight says they're just thinking too hard about it, it's just a joke. Still, others say it isn't entirely inaccurate, considering he did a fair amount of wandering in his youth. And some of the gangsters under his command, who are by now adults themselves, fondly remember listening to his stories from Earth, in which knights errant often performed their duties in the name of a lady, point to Amelia as the lady to whom the don has devoted his life as her faithful knight, whether the quests he carries out on her behalf require him to leave home or not. It has also been pointed out by some that Knight's choice of surname serves as proof that his sense of humor can be just as silly as that of Amelia, which may be one reason he is one of the few close friends she has.