It started with cupcakes, of all things.
Steve had walked into the kitchen one afternoon to find Tony and Natasha in the middle of baking. There was a platter of cupcakes on the counter and Natasha was carefully pulling another batch out of the oven while Tony vigorously stirred a large bowl of white frosting.
“What's the occasion?” Steve asked.
“Russia Day,” Natasha said with a smile. “Tony's looking forward to trying a traditional Russian meal.”
Steve frowned. “I didn't know cupcakes were Russian.”
“We spiked the frosting with vodka,” Tony said. He waved the spoon around, splattering himself with little flecks of frosting. “It's a brilliant idea and I'm only upset that I didn't think of it first.”
Natasha rolled her eyes. “Don't mind him, Steve. He's already had half a bottle of vodka.”
“Did not,” Tony protested. “Most of it's in the frosting.”
“And most of the frosting's on you,” Natasha shot back.
Steve was forced to agree with her. Tony's hands were sticky and there were white smudges on the collar of his black t-shirt. Steve was pretty sure making frosting wasn't supposed to be such a messy affair, but Tony seemed to have a knack for getting himself filthy. It reminded him of seeing Tony down in his lab, covered with grease and sweat and-
He blinked. Weird. His mind didn't usually wander like that.
Natasha and Tony had gone back to their baking, playfully bickering with each other. It was almost like he wasn't there anymore. Fine by him. It was a rare sight to see Tony and Natasha getting along so well and he was content just to observe.
They actually worked efficiently as a team, Steve was surprised to note. The cupcakes were turning out beautifully. And Tony was a shockingly good cupcake decorator for a man who never cooked anything besides instant noodles. The way Tony squeezed the pastry bag, carefully pumping out lines of creamy, white-
Okay, no. He was not letting his mind wander again. Tony was just frosting some cupcakes. It was all perfectly innocent.
Tony glanced surreptitiously at Natasha and then lifted the pastry bag to his mouth. Toy's eyes slid shut and then his dextrous engineer's hands began gently kneading and squeezing the bag.
He watched Tony's throat work as he swallowed. He was practically drinking the stuff, making small noises of contentment. Steve was ashamed of himself, but he was absolutely enthralled by the sight. He wasn't sure he could move even if he wanted to.
But then Tony opened his eyes and met his gaze. Tony's eyes went wide and he hastily slipped the bag out of his mouth.
And now there was frosting smeared across his mouth and chin.
“You got uh, a little on your face,” Steve said faintly.
“Where?” Tony licked at the corners of his mouth.
Steve averted his eyes. “Yeah, that's-you got it.”
“Tony,” Natasha said sternly. “How are we going to frost all these cupcakes if you eat all the frosting?”
“We don't have any more powdered sugar, idiot. I already told you that.”
“It's okay,” Steve said quickly. “I'll run to the store.”
“You don't have to do that,” Natasha said.
“No, I uh, I need the exercise. Missed my morning run.” He went for the door as fast as he could.
Behind him, he could hear Natasha say, “Tony, did you just fit an entire cupcake in your mouth?”
Steve didn't dare look back.