Chicago basketball is a small world by reputation and a smaller one by family. Sean Areon Dockery was born into the inside of it on January 5, 1983, the son of Steve Dockery, the longtime head basketball coach at Corliss High School on Chicago's South Side, and Sherry Dockery. He grew up in a household where the game was a vocabulary before it was a sport. His younger brother Sherrod and his sister Cookie share the surname; the family lives are stitched into the city's basketball ecology in the way that only Chicago basketball families really are. At eleven, in a moment that suggests the multi-sport athlete he might have become, Dockery threw a no-hitter in a baseball game. The rest of his childhood was elsewhere.
By the time he reached Julian High School on the South Side — a Chicago Public League program with a long history of producing serious players — he was already, in the local conception, the next great Chicago point guard. He was coached by Loren Jackson. As a junior he averaged 21 points, 8 rebounds, 9 assists, and 5 steals per game. As a senior in 2001-02 he averaged 28 points, 7 assists, 4 rebounds, and 4 steals, captained Julian to a 20-9 record and a Chicago Public League conference championship, and produced individual statistics that have not been touched in Illinois high school basketball since: when he graduated, he held the state career records for assists (1,179) and steals (664), and finished third all-time in scoring. He scored a career-high 53 points in a single game. He was named the reigning Chicago Player of the Year, was a four-time All-Public League player, three-time all-area, three-time all-state. Student Sports ranked him the nation's tenth-best playmaker. RivalsHoops.com had him at No. 9 nationally. He was named Street & Smith's preseason fourth-team All-American for the 2001-02 season. He was a McDonald's All-American, scoring two points with three rebounds and two assists for the East team in the All-American Game in New York City — and at the same selection event he played alongside two players he would soon room with, J.J. Redick and Shelden Williams. (Earlier that summer all three had played together on the gold-medal North squad at the 2001 USA Basketball Men's Youth Development Festival in Colorado Springs.)
The recruiting question for Dockery's senior year was not whether he would play in a major program; it was which of three Chicago-favored point guards Mike Krzyzewski's staff would land. Duke had pursued Jarrett Jack of Worcester Academy, Anthony Roberson of Saginaw, Michigan, and Dockery — and ultimately committed to Dockery as the floor general for the recruiting class of 2002. The class he joined was a serious one: Shavlik Randolph (a top-three national recruit), J.J. Redick (the legendary Roanoke shooter), Shelden Williams (the Oklahoma center who would become the No. 5 overall pick in the 2006 NBA Draft), Lee Melchionni (the Pennsylvania left-handed shooter from a basketball-saturated family), and Michael Thompson. Dockery would room with Williams. He would spend four years at Duke alongside the same group of teammates he had met as a McDonald's All-American the previous spring.