But beyond those viral moments, the first lady has, at times, looked unenthusiastic if not downright displeased as the first couple has been paraded through diplomatic protocol and photo-ops in Saudi Arabia, Israel, and Rome. Her look is a stark departure from first ladies of the past, who, generally, have displayed permanent smiles while accompanying their husbands at public events.

No matter what you think of Melania Trump or her husband’s politics, there is a subtle strength in her stone-faced expression during these command performances. As the Washington Post‘s Robin Givhan puts it:

For a woman who was once a model, who ostensibly is practiced in the art of nonverbal communication, the willingness to forgo a grin seems less like an accident and more like the tiniest declaration of personal control and rebellion. She is here for you, but she is not going to perform for you.

In a way, Melania Trump’s countenance embodies the burden of being first lady—a ceremonial role, based largely on appearances, that is hoisted on a woman only because of her relationship to a powerful man. In calling for the office of first lady to be abolished in November, Politico‘s Jack Shafer argued that by giving the president’s wife a federal budget and nonstop press coverage, “we endorse a pernicious kind of neo-nepotism that says, pay special attention to the person not because she’s earned it or is inherently worthy of our notice but because of who she’s related to by marriage.”

But at a more fundamental level, Melania Trump’s facial expression is an affront to a society that still demands that women—rather than determine their own emotional state—always smile instead.

A version of this story first appeared in Fortune’s World’s Most Powerful Women newsletter. Subscribe here.