Tony introduces them.
He's known what Rhodey's mark is--a blue circle, inset with a golden square--since they were sharing a room at MIT together. He'd realized Nebula's mark, man of metal entirely in silver, was Rhodey the moment he saw it on her stomach where she lifted her shirt to show him, her face blank of all expression.
Nebula helps him get back to Earth, and one of the few good, happy moments he has in the following few days is calling Rhodey and Nebula into the medical bay he's been grounded to at the same time.
"Rhodey, this is the lady of your soul, the woman of your heart, the blue to your silver," he says, holding out an arm to gesture to Nebula. She's looking back at him, clearly unimpressed with the dramatic introduction.
Rhodey chokes on the coke he's holding and Nebula, light of his life even if he doesn't quite know it yet, walks right over and hits him hard on the back. He coughs and stares at her, and then at Tony, who shrugs, and then back at her.
"Is he being serious right now, or--"
"I believe he is referring to the mark that humanoid species are born with to signify the second halves of their souls," she says, her voice low and deep. Tony couldn't tell you how he knows that she's hopeful and terrified, but he does: she's practically vibrating with it.
Rhodey just looks lost and disbelieving. Fair: he's old enough now that he'd resigned himself to never finding his other half. He and Tony had talked about it once, over too much brandy and wine at some wedding he hardly remembers otherwise.
You don't need to find your soulmate to be happy, of course--he and Pepper are proof enough of that--but obviously it helps.
Rhodey shakes his head, bemused, and pulls up his sleeve to show her the blue and gold mark on his arm. If Tony notices that Rhodey is flexing his muscles a bit more than he needs to just to show off the mark, well, that's to make fun of him for later.
Nebula lifts her shirt after staring at Rhodey's shoulder for a long moment.
The woman has absolutely no modesty. Tony looks back at Pepper, raising his eyebrows and she stares at him incredulously as if to say, That's how you tell Rhodey you found his soulmate? That?
Hey, he's in a hospital bed, recovering from a battle wound, and he's sleeping sixteen hours a day. Give him a break. They're lucky he even remembered. (Of course he remembered. He owes Blue his life, and Rhodey is Rhodey.)
"Okay," he says, clapping his hands together and grimacing slightly. "You two kids go have fun. Introduce her to ice cream, Platypus. I promised I would but I'm not exactly in the position for it just now."
Rhodey rolls his eyes and Tony and smiles softly at Nebula.
"Would you like to, uh, go out? Get ice cream or--anything?"
Nebula nods, short and concise. "I wish to try ice cream, yes. This would be... pleasurable."
Rhodey pauses, and then grins. "Alright, let's go. You have to try Rocky Road."
"If we are to walk on rough terrain, I will require my boots."
"Uh, no, Rocky Road is a flavor. Actually, maybe we should just start off with chocolate."
Tony grins. He'll be the best man at the wedding, same as Rhodey will be at--
He turns to Pepper, his eyes wide, and says, "Double wedding."
She looks at him, puts down the tablet in her hands, and says, "No."