The more bewildering challenge, Mr. Sourisseau said in a recent interview, has been adapting to Charlie Hebdo’s instant transformation from a relatively obscure, parochial French publication to an international symbol, celebrated by free-speech advocates. Its two dozen cartoonists and writers, who previously enjoyed some degree of anonymity, moved this month to a new, heavily fortified newsroom with bulletproof windows, a panic room and a labyrinth of safety doors — security measures that cost 1.5 million euros, or $1.65 million. They live furtively, under 24-hour police protection.

Perhaps more troubling, the solidarity that once bound Charlie Hebdo’s close-knit staff has cracked under the trauma of the attacks and discord over how to divide the publication’s newfound wealth. A surge in subscriptions and newsstand sales from supporters has brought millions to the newspaper’s coffers but has also led to bitter internal squabbling over how — and how much — money should be reinvested in the paper and distributed to the families of the victims.

“It was a bit of a double punishment,” Mr. Sourisseau, a soft-spoken former railway worker, said of the upheavals that have shaken Charlie Hebdo in recent months. “When I left the hospital, I thought naïvely that we would all go back to working together as before. I had no idea that there would be so much chaos.”