Angela Merkel’s marathon tenure as Germany’s leader may have officially crossed the finishing line with September’s federal elections, but her final lap of honour could take some time. Depending on the pace of coalition talks between the politicians hoping to fill her shoes, she may yet give one more of her annual TV addresses in a caretaker capacity this Christmas.

Still, as a new generation of German leaders rises to the fore and Merkel recedes into the background, the contours of her legacy are becoming easier to distinguish. There are quantifiable historic firsts: 16 years in office make her the joint longest-serving chancellor of the postwar era, equalling the record of her former mentor Helmut Kohl. She’s the first German chancellor to have the wisdom to step down of her own will, at the end of a full term.

She’s the first female German head of government, the first with a scientist’s training, and the first to have grown up in a socialist command economy. She may go down in history as a once-in-a-century political adaptor, connecting two differently hardwired systems kept apart by the Berlin Wall.

Yet it’s also possible that Merkel may not be remembered as a pioneer, but as the last example of an idea that feels increasingly old-fashioned in an age where more and more political tribes are built around personal identity: leadership as an exercise in ego suppression, holding high office as tantamount to covering the very traits that make you unique.

Hungarian-American author Kati Marton is especially fascinated by this aspect of Merkel’s tenure: the intense privacy of a woman who rose to power in an era of oversharing.

“After several decades, Germans are not tired of her image, her voice, her looming persona – because Merkel does not loom,” Marton writes in her biography, in response to the German leader’s enduringly high popularity ratings. “Despite knowing little about their chancellor’s private life, other than that she comes across as leading a life not so different from their own, Germans thrice reelected her, each time by a comfortable margin.”

From Marton’s US perspective, the contrast is especially glaring: while Donald Trump’s stint in the White House became a reality TV show, broadcast in real time through tweets and continual leaks, Merkel’s chancellory is famously gossip proof. Marton writes that her obsession with privacy “verges on paranoia”. The world was privy to Trump’s every idle thought via Twitter; Merkel, however, keeps no journal, does not use email, and “texts only briefly and when necessary”. Her long-standing, mostly female set of advisers is not only intensely loyal but almost invisible to the media’s eye.

Those who have been unwise enough to blab found themselves banished from her inner circle: one political ally, Marton writes, was never allowed back into Merkel’s confidence after releasing a four-word email with the following explosive content: “Thanks for the suggestion, AM.”

Few Germans are even aware that their chancellor has a sister and a brother, because they lead ordinary lives doing ordinary jobs and never speak to the press. Her first husband, Ulrich Merkel, whose surname she kept after their divorce in 1982, once gave a reluctant on-the-spot interview in which he praised his ex for her stance during the refugee crisis of 2015.

Perhaps after Merkel has left office proper there will be a biography that will lift the veil on her private motivations; Marton’s diligently compiled but often overtly reverential chronological overview is not it. In spite of numerous interviews with close advisers, touted as “circumventing the chancellor’s extraordinary need for control”, there are few revelations here that cast a new light on her leadership.

Marton notes how Merkel was the daughter of a Protestant pastor and the former head of a party with the word “Christian” in its name. She believes her “private faith, and the Bible, would steady her sometimes rocky path”, as well as provide a connection with the first US president she met in office, George W Bush. She may well be right, but this book doesn’t present any evidence to back up that claim, nor does it explore how Merkel’s specifically East German Lutheran brand of Christianity may have influenced her.

Marton believes Merkel to be a feminist, even if the chancellor herself only used the term to describe herself for the first time last month (in a panel discussion with the the novelist Chimamanda Ngozi Adichie). But as with her East German background, the chancellor’s sex was never converted into a policy priority. In fact, little of Germany’s progress on gender equality over the last 16 years can be directly put down to Merkel’s leadership: she initially opposed her labour minister Ursula von der Leyen’s proposal for legally mandated gender quotas for senior management positions.

At times, there is a slightly comical sense that the qualities Merkel’s biographer finds most intriguing are also those that most elude her: Marton, who also grew up east of the Iron Curtain and went on to become an ABC News foreign correspondent and marry the influential late US diplomat Richard Holbrooke, cannot help but slide her own story into the footnotes. Not quite the lesson one would have expected a writer to draw from studying a politician who managed to command authority by leaning out rather than in.

In one aside, Marton mentions that she once met Merkel at a lunch party hosted by the film director Volker Schlöndorff in September 2001, long before she started her biography. The writer Susan Sontag was also in attendance, she reveals, though sadly her memory of what words passed between the two women is sketchy. The pair were “a study in contrasts”, apparently: “Sontag, expansive; Merkel, the active listener.”

Perhaps while we wait for Merkel’s inner circle to go public and help produce the first truly illuminating biography of her tenure, we need storytellers to fill in the gaps. A chamber play on love, life and the way we live now featuring Merkel and Sontag: now that would be revelatory.