After one of her first encounters with Vladimir Putin in 2002, Angela Merkel joked to aides that she had passed the 'KGB test' by staring straight into his eyes without averting her gaze.
Unlike presidents in Washington - George W. Bush claimed to have gotten a glimpse of Putin's soul and Barack Obama promised to 'reset' relations with Russia - the German chancellor has never harbored any illusions about the former Soviet agent, nor hopes that she might change him.
It is this hard-nosed realism, born of Merkel's own experience growing up in a Soviet garrison town in East Germany and reinforced over a turbulent 14-year relationship with Putin, that has earned her respect in the Kremlin and thrust her into the potentially risky role of chief mediator in the Ukraine crisis.
When Merkel and Putin interact it is a clash of polar opposite world views, aides to the chancellor say.
For Merkel, the physicist, the fall of the Berlin Wall in 1989 was a godsend that launched her extraordinary career as a politician.
For Putin, who was living in the East German city of Dresden at the time, it was a calamity that led within two short years to the collapse of the Soviet Union - an event the Russian leader has described as the biggest geopolitical catastrophe of the 20th century.
But despite different outlooks, Merkel and Putin, born less than two years apart, speak each other's language - literally and figuratively.