These days, Natasha's job involves a lot more literal ass-kicking than it used to, but she was trained in espionage first, and has worked with and trained many others since. She found, over time, that the one thing no one can teach is intuition: taking the measure of a gesture seen once, understanding what an expression means in a fraction of a second, judging the emotional level in a room. It's instinctual, it's cultural, and it is the most vital survival skill she has ever known.

So sometimes Thor drives her crazy with the hand-kissing.

Natasha thought she had it figured out when he did it with Jane and Pepper. She adjusted her theory slightly when he included Madeline, the Stark Tower chef. But when he bestows a kiss on the hand of Wilson, the guy who runs the soup kitchen they just saved from mole people, she gives up and asks.

"It is a pledge of respect and service," he tells her, puzzled, like she's the confusing one. "Informal, of course, and any bonds of allegiance would take precedence. Is it not the same here?"

"Not really," she says. "Mostly, it's seen as a romantic gesture."

"Ah. Yes, it can be that as well, between two who are already intimate," Thor agrees. "But the meaning holds true."

Natasha thinks back to the times she's seen Jane receive kisses before leaving gatherings, correlates to the noise level in the Tower at night, and lifts an eyebrow at Thor. "Service, huh?" she asks.

"Of a sort," Thor says, smug.

Natasha chuckles. "Lucky Jane."

He inclines his head to her, a wicked sparkle in his eyes. "As you say."