In Arnaud Desplechin’s latest film, “A Christmas Tale,” a typically agitated and unpredictable scene plays out in which Jean-Paul Roussillon’s Abel, patriarch of an impossibly conflicted family that is gathering for the holidays, spots his upset grown son Henri, played by Mathieu Almaric, climbing down the side of the two-story house as if to escape the hellish clan reunion.

Henri almost makes it to the bottom — and falls. “Why didn’t you take the stairs?” Abel sensibly asks.

The son can’t really say why, but the real answer is: Because this is an Arnaud Desplechin film, where characters always fight against their own best interests, where every personal insight stems from a well-earned but time-consuming quest, where elders bemuse and befuddle their children and vice versa, where no action is so illogical that it couldn’t happen but is often surprising enough that it couldn’t be anticipated.

The nearly comprehensive survey of Desplechin’s films from 1991 to the present that the AFI Fest has organized with the Los Angeles County Museum of Art ranges from his first mini-feature from 1991, “La Vie des morts” (about another family in conflict dealing with a son near death), to four of his six features: “La Sentinelle” (1992), “My Sex Life … or How I Got Into an Argument” (1996), “Esther Kahn” (2000), “Kings and Queen” (2004) and “A Christmas Tale” — as well as his beautiful, little-seen autobiographical doc about his own family, “L’Aimee” (2007).

Each film, like his characters, goes its own way. “La Sentinelle” is a subdued thriller about a young doctor uncovering Cold War secrets. The English-language “Esther Kahn” explores the complex behavior of a young actress. And the endlessly fascinating trio of “My Sex Life,” “Kings and Queen” and “Christmas Tale” are grand comedy-dramas with huge emotional swings and bigger ideas.

As critic Kent Jones has described what is possibly the most ambitious body of films by a French director in the past two decades, “At his best, which is most of the time, Desplechin is like an explorer combing and hacking his way through virgin territory, charting the landscape but never altering it according to an existing standard of beauty or dramatic interest.”