Bruce Banner had become an expert in self-denial since the Green Years began, but he couldn't bring himself to regret being in a highly air conditioned lab when August lay over New York City like a smelly wet blanket. Even with Tony Stark being weirdly brilliant all over Bruce's carefully arranged Petri dishes.

"Nanotech can do what cells do, Brucie," Tony said, waving his hands. "That's what it's designed to do."

Bruce pushed up his glasses and continued looking at his microscope. "And that wins as the most terrifying thing you've said today."

"Wow, and it's barely noon."

"Excuse me, sir," Jarvis said from a nearby speaker. "Dummy and the others wanted to know if you were going to join us this year."

Tony blinked. "Join you?"

"It is the 5th, sir."

"Good God, is it August already?"

"Yes, sir."

Tony looked carefully at Bruce but addressed Jarvis. "How long do I have?"

"Roughly twenty minutes. Given the time delay, I've already begun the uplink."

"Good idea. I'll try to get down there in time."

"Very good, sir."

Bruce frowned. "The International Space Station isn't that far, so there's no real time delay. Where are you trying to link to, the Moon?"

Tony took a deep breath. "Mars."

"Good lord, who's on Mars?"

"Not who, what. The Curiosity Rover. He landed on Mars on August 5, 2012, and he's been trundling along ever since."

Bruce smiled. "And you call him up every year to say Congratulations?" He blinked at the fierce look on Tony's face.

"His people at Goddard programmed him to have a little celebration every August 5th." He glowered off into the distance. "Every year on this day, poor little Curiosity stops what he's doing and sings Happy Birthday to himself, all alone on whatever barren wasteland he finds himself on. Goddard doesn't even bother to call him, they just programmed him to sing to himself once a year."

Bruce knew a lot of people would laugh, but he remembered birthdays no one else remarked on, indifferent cards that arrived weeks late. "How long have you and Jarvis and the bots been singing to him?"

Tony grinned and pretended his eyes weren't a bit damp. "Since 2013. One of the techs mentioned it at a conference just after Curiosity landed. He's never had a birthday party alone."

Bruce nodded and began shutting down his experiment. "Will there be cake?" He grunted as Tony abruptly hugged him from behind.

"Pepper's bringing the cake. If we hurry, Dummy can make you a personalized party hat."