Kim Jong-un, probable heir apparent of Kim Jong Il, is believed to have been born in 1983 or 1984 to Kim's third wife (Ko Hyong-hui) and is allegedly his father's favorite son. There are also reports that Kim Jong-un may share some of the ailments of his father, such as diabetes.
Unlike his brother Kim Jong-chol, Kim Jong-un has a more forthright character and, some sources say, has exhibited leadership skills. He is rumored to have studied at the International School of Berne in Guemligen, Switzerland. There are varying reports that he speaks German, French, and English. Upon returning to North Korea sometime after 2000, his studies continued, most likely at Kim Il Sung Military University.
In 2004, reports began to surface that he and brother Kim Jong-chol were accompanying their father on inspections of military installations. In 2007, a flurry of reports emerged placing the third son in either the Korean Workers' Party's (KWP's) powerful Organization Guidance Department, where Kim Jong Il began his career in 1964, or the Korean People's Army's influential General Political Bureau. Both of these bodies are charged with surveillance and monitoring of the regime's powerful party, military, and security bodies.
When the succession will be made public is a critical question. Some Pyongyang watchers speculate that it will be attached to an auspicious date in North Korean history. Many point to April 2012, which would mark the 100th anniversary of Kim Il Sung's birth. Of course, the health of Kim Jong Il, which has appeared to worsen in recent months, will probably drive the timing of this announcement.
[Excerpt of an article by Ken E. Gause, senior analyst at nonprofit think tank, who has studied the North Korean regime for two decades.]