Barack Obama's decision last year to ask his once-bitter primary foe Hillary Clinton to be secretary of state shocked the Clintons as much as everyone else.
Critics posed a simple question: how to reconcile Hillary Clinton's role with that of her globe-trotting, larger-than-life husband, whose bulging book of business contacts could pose possible conflicts of interest?
"When she became secretary of state, the question was, 'what is Obama going to do with Bill Clinton?'" said Julian Zelizer, a historian at Princeton University.
"Now the answer seems to be that he is going to use Bill Clinton."
Even critics of the Clintons had to admit last week that the statesmanlike ex-president was pitch-perfect in his sensitive encounter with Kim and self-effacing on his return.
US intelligence analysts are meanwhile awaiting a priceless briefing on the state of Kim's mind, health and regime -- from America's most seasoned diplomatic player and master of political psychology.
Some observers are now wondering whether Clinton, who heads a global charitable foundation, may get future sensitive diplomatic missions.
"(Clinton) got the administration out of a difficult jam and Obama will be happy to use him again," said Zelizer.
Clinton might be a candidate to open an unofficial channel to Pyongyang, should the Stalinist regime come back to the nuclear negotiating table.
But such a role may be seen as a reward for "bad behavior" by Pyongyang, and undermine the six-party talks to which the Obama White House is committed.
So perhaps Clinton might be used elsewhere, where his prestige and semi-official status could open doors closed to other US luminaries -- in the Middle East or Myanmar for instance.
Some observers, though, feel that given Clinton's wide business and political profile, his appearances must be rationed.
And Obama, as a young Democratic president finding his way, may not relish the sight of the old sage galloping around the globe.
Clinton may also detract from his wife's evolving role: this week Clinton's trip behind North Korea's iron curtain overshadowed her trip to Africa.
"Personally, I see this as a one-time thing for him," said Tom Baldino, professor of political science at Wilkes University, Pennsylvania.
"He may have done the job so well that he may have come close to eclipsing his wife. For her sake, he can't do this on a regular basis."
For better and for worse, the Clintons have in two decades in top-rank US politics come as a joint package -- or "two for the price of one" as the ex-president's 1992 campaign had it.
In good times the former president boosts his wife's political profile and leverage.
But often (especially with his red-faced tirades in her epic 2008 campaign for the presidency), Clinton can harm her hopes.
Bill Clinton's political career, encompassing impeachment and the first two-term Democratic presidency since Franklin Roosevelt, often seemed to follow a cycle of near-disaster then redemption.
So there was a familiar feel about his mission to North Korea, which showcased his top-notch diplomatic skills, and drew a redemptive embrace by Obama, following the bitterness of 2008.
During the campaign, many Obama backers fumed at the ex-president's antics and felt he veered onto racial ground while Clintonites felt Obama did not give the former president his due for bitter political battles won in the 1990s.
Another redemptive moment of the Clinton mission came when he bonded in a tight embrace with Al Gore on returning to the United States.
Gore founded "Current TV", the station for which reporters Laura Ling and Euna Lee were working when they were arrested by the North Koreans, and asked Clinton to help win their release.
The two men had left office in 2001 estranged. Clinton thought Gore deserted his legacy and Gore blamed Clinton's affair with intern Monica Lewinsky for his 2000 general election defeat.
So for the first time in years, the big beasts of 1990s Democratic politics -- the Clintons and Gores -- are reconciled, and uniting left-of-center powerbases with Obama, the new party champion.