Disclaimer: Hetalia does not belong to me, it belongs to Hidekaz Himaruya. English isn't my first language, but i did my best.
Hyung Soo is the headcanon name for North Korea and Yeobo means "Honey" or "Darling", it is a Korean word.
The first time Natalia says it, Yong Soo actually doesn't know what she's saying. To be fair, Natalia had just given him a pretty spectacular kiss, and he couldn't really tell what language she was speaking between the mumbling and the happiness. But then Natalia repeats herself again, louder, and Yong Soo blinks at her.
"Are you trying to call me 'Yeobo'?" he asks, and Natalia turns bright pink and gets that stubborn set to her jaw that says she knows she's done something wrong, and isn't willing to accept less than perfection.
"No," Natalia whines, and she sounds so cute, like such a cranky little girl, that Yong Soo has to roll over and kiss her.
"Na-tasha" he sing-songs, pressing kisses in the spots under her jaw where he knows it makes Natalia all weak and shivery.
"Well, the Koreans call their spouse like that" Natalia says, like she's trying to hold onto being grumpy, but she relaxes slowly the more Yong Soo kisses her and runs his hands up and down Natalia's sides.
"You are not Korean," Yong Soo points out, pulling back and smacking a kiss on Natalia's nose, because it always makes her crinkle it and smile, charmed against her will. "Is okay. I like you calling me 'Yong Soo' just fine."
"Is that your way of telling me I'm saying it wrong?"
"Very wrong," Yong Soo agrees. "Is okay. Like I said, you are not Korean."
"You can teach me," Natalia says, just like when she'd insisted on learning a few basic phrases to suck up to Yong Soo's family. Her accent is terrible, thicker that Yong Soo's is in English or Belarusian, but his family had looked really touched the first time Natalia thanked them in halting Korean for cooking for them, so maybe there's something to it.
"Why do you need to learn?" Yong Soo asks, curious, and his wife turns bright pink again and avoids his eyes, which is... interesting.
"I, um, might be a little jealous?" Natalia asks the ceiling. "The people of your country have a nickname that makes them happy? And I can't use it?" Yong Soo's really glad Natalia's looking at the ceiling, actually, because he's sure the expression on his face is probably pretty embarrassing, if the amount of sheer, stupid adoration he's feeling brewing hot and happy in the pit of his stomach is anything to go by.
"Okay, we work on it," he concedes, like he doesn't always concede everything to Natalia just to see the pretty, elegant smile he fell so in love with in the first place. He has to close his eyes and kiss Natalia before he promises her something even more ridiculous, and judging by the way Natalia moans into the kiss and rolls on top of him, she's ready to go for it and forget about nicknames for a while, which is just fine with Yong Soo.
Natalia drops it for a few days, which Yong Soo decides, or maybe hopes, means that Natalia's forgotten about it. She's pretty much forgotten about everything but her work as a nurse. She've got a hard at her work for a couple weeks, and then she's gone into one of her perfectionist fits, staying late at the hospital and blocking out the rest of the world, including Yong Soo. And he knows he should be mad, probably, that he's barely seen Natalia for half a week, but mostly he's just fondly resigned. This is Natalia Arlovskaya, and Yong Soo always knew this is what dating her would mean, long before he even knew he wanted to be the one doing it.
Still, it doesn't mean he can't nag. He figures that's sort of what being a good boyfriend is.
Yong Soo is resting his elbows on table and watching as Natalia methodically eat her piece of cake, meanwhile he drinks his coffee. "You're doing your job great."
"Not great enough," She says, look more tired than anything.
"Help people not enough anymore?" Natalia's glare is a pretty clear answer "Come over," Yong Soo wheedles. "I'll make dinner. Dumpling misses you."
"Don't bring our dog into this."
"Fine, so I miss you."
"Yeobo..." Ah, Yong Soo smiles. There it is. Of course the blonde Belarusian uses the nickname again just to get what she wants, she's smart. It's one of the things Yong Soo likes about her.
"You are getting better," he says, because it's true. Natalia's clearly been practicing her accent. He bets if he got his hands on her laptop, he'd find Youtube clips with how-to guides in the browser history. Natalia still says 'Yeobo' with too many syllables, slowly, like she's not sure she's getting it right. It's all terribly, horribly adorable.
"I'm gonna get better at this, too" Natalia says stubbornly. She gives Yong Soo one soft kiss, reaching up to tease the short hairs at the base of Yong Soo's neck the way he likes. That pushes the kiss over the border to cruel, because Yong Soo hasn't gotten laid in four days (not that he's counting), so he's not ashamed of making a bereft little moaning noise when Natalia pulls away.
"You are a bad woman," He tells Natalia. "And you are lucky I am in love with you and you are so pretty, otherwise I would be very angry right now." Natalia just laughs.
"Say Good Night to Dumpling for me," She shouts, walking away, like she knows Yong Soo's going to listen to her just because he's in love with her and she called him Yeobo and is cute. And the worst part is that she's right, because Yong Soo does leave, go home alone late at night, and tell Dumpling that Natalia says Good Night.
Little Dumpling seems unimpressed, bordering on judgmental, and then goes back to play with his ball. But he's a puppy, so what does he know, anyway.
Natalia mostly only calls him 'Yeobo' when they're in private, which is good, because Natalia slips up and uses once in public and Yong Soo walks around with such a stupid expression that Hyung Soo, who was there visiting them, asks him three different times whether what happened before he figures out what Yong Soo's smiling at and rolls his eyes.
"You know I've got nothing against you two doing your thing," he say "I'm just saying, there's a reason people have a problem with such love display, and it's this touchy-feeling shit right here."
"Shut up, Hyung," Yong Soo barks, the tips of his ears are bright pink, which doesn't do much either for his gravitas or for Yong Soo's ability to stop smiling at him like an idiot.
"No, I think it's cute," Hyung Soo says, grinning like the little shit he is. "It's nice to see that the romance hasn't gone out of your relationship after all this time. It's an inspiration to the rest of us."
Yong Soo's clearly more amused than angry, but he's also turning progressively pinker, so he grabs his brother in a headlock and wrestles him to the floor until he gives. It takes about five seconds. Hyung Soo's pretty weak.
So 'Yeobo' is a private name. It's something Natalia says to wake Yong Soo up late at night when he's half-asleep on the couch because he was playing videogames and needs to be cajoled to bed. It's something Natalia calls him first thing in the morning when she's made Potato Pancakes because she can't let her husband eat his sad cereal another day. It's the name Natalia whispers when she hugs Yong Soo after a long day and tells him she's tired. Natalia says it the way he used to call her his angel when he kissed her before a business travel. Yeobo, when Natalia says it, means home and love in a way he didn't know he was missing until Natalia started using the name, the kind of love that makes Korea and all of his friends and family feel less far away when he doesn't have time to Skype or text them back, the kind of love that anchors him and makes him feel more like this is somewhere he belongs.
He just really wants Natalia, right then. Yong Soo finds her in the living room, flipping through an old book and petting their cat, Pasha, who's curled up asleep next to her. Natalia doesn't look up when Yong Soo shoos Pasha off the couch or when he takes his place, she just automatically lifts her arm for Yong Soo to crawl under and then begins stroking his black hair, like she never even noticed a difference. "Something wrong?" she asks, bending down a page corner to mark her place and tossing aside the magazine.
"No," Yong Soo says, and then, because even a lie of omission feels like lying to Natalia, "My brother was asking why I let you call me 'Yoebo."
"Why you let me say it wrong, you mean," Natalia corrects, and Yong Soo shifts uncomfortably. He didn't know she noticed that. It's not like he purposefully told her to do the wrong thing, he just... stopped pointing it out if Natalia messed up. "Why don't you correct me?" She asks quietly.
"Would you try and fix my accent?" He asks, and Natalia looks at him for a moment with so much exasperation mixed with pure, unguarded adoration that Yong Soo feels lit up with it.
"That's not even the same thing," Natalia says eventually. "You're trying to distract me so you don't have to answer the question."
Yong Soo tilts his chin up to kiss Natalia's neck instead of answering. He doesn't quite know the answer himself, besides that he can't deny her anything, and that the way his wife says "Yeobo" is somehow that perfect blend of Belarusian and Korean that makes it feel like it's something brand new. So instead he says, "Maybe later. Turn on the TV."
Natalia grumbles but does what she's told before she sinks into the couch with an absent kiss to the top of Yong Soo's head. And when Yong Soo closes his eyes to Natalia's warm weight against him and the sounds of the TV, it feels perfect, like home, their home.