Today we consider Orion Clemens, who clerked in St. Louis during the mid-1800s for lawyer Edward Bates. Following his stint as Bates' clerk, Orion didn't quite make it as a lawyer, then watched as Bates hit it big following Abraham Lincoln's election to the presidency.
Having no fear of Missourians, Lincoln appointed Bates the nation's next Attorney General. His former law clerk was aware of the unwritten law that commands law clerks, whenever possible, to latch onto the government appointments of their former bosses. So Orion wasted no time in weaseling an invitation to become Secretary of the Nevada Territory.
Meanwhile, Orion’s little brother Samuel was just to the north near Hannibal, where he was doing a short stint with a Confederate-leaning militia. It was there, after just a few weeks, that Samuel learned he had “no desire to kill people to whom [he] had not been introduced.”
It was this fortunate realization that led Samuel to accompany his brother Orion to Nevada. In Nevada, Samuel began signing his newspaper stories “Mark Twain.” Other experiences during the trip west became fodder for the book Roughing It, which recently figured into this very interesting New Yorker article about the Mormons.
In Orion's later life, his brother became famous but he didn't, despite his hard work as a law clerk for Edward Bates. Orion died in 1897 at the age of 73.
(Source note: Most of the facts in this post are from The Singular Mark Twain by Fred Kaplan.)