Amid his siblings’ shenanigans, Seif, the president’s second-eldest son, had been “opportunely disengaged from local affairs,” spending the holidays hunting in New Zealand. His philanthropy, the Qaddafi International Charity and Development Foundation, had sent hundreds of tons of aid to earthquake-ravaged Haiti, and he was seen as a reasonable prospect to succeed his father.

The same 2010 cable said young Libyan contacts had reported that Seif al-Islam is the ‘hope’ of ‘Libya al-Ghad’ (Libya of tomorrow), with men in their twenties saying that they aspire to be like Seif and think he is the right person to run the country. They describe him as educated, cultured, and someone who wants a better future for Libya,” by contrast with his brothers, the cable said.

That was then. Today the young protesters on the streets are demanding the ouster of the entire family, and it was Seif el-Qaddafi who declared on television at 1 a.m. Monday that Libya faced civil war and “rivers of blood” if the people did not rally around his father.

As for the 68-year-old Colonel Qaddafi, the cables provide an arresting portrait, describing him as a hypochondriac who fears flying over water and often fasts on Mondays and Thursdays. The cables said he was an avid fan of horse racing and flamenco dancing who once added “King of Culture” to the long list of titles he had awarded himself. The memos also said he was accompanied everywhere by a “voluptuous blonde,” the senior member of his posse of Ukrainian nurses.

After Colonel Qaddafi abandoned his pursuit of weapons of mass destruction in 2003, many American officials praised his cooperation. Visiting with a congressional delegation in 2009, Senator Joseph I. Lieberman, Independent of Connecticut told the leader and his party-loving national security adviser, Muatassim, that Libya was “an important ally in the war on terrorism, noting that common enemies sometimes make better friends.”

Before Condoleezza Rice visited Libya in 2008  the first secretary of state to do so since 1953  the embassy in Tripoli sought to accentuate the positive. True, Colonel Qaddafi was “notoriously mercurial” and “avoids making eye contact,” the cable warned Ms. Rice, and “there may be long, uncomfortable periods of silence.” But he was “a voracious consumer of news,” the cable added, who had such distinctive ideas as resolving the Israeli-Palestinian conflict with a single new state called “Isratine.”

“A self-styled intellectual and philosopher,” the cable told Ms. Rice, “he has been eagerly anticipating for several years the opportunity to share with you his views on global affairs.”