Eijiro had been acting suspicious. Despite Katsuki repeatedly asking him what the fuck was up, Eijiro always had a retort, a quick excuse on his tongue or a flat out denial.

Tired of feeling like a crazy person, Katsuki devises a plan to get to the truth.

A business trip, one that will take him out of town and away for a weekend.

It hurts him to see how quickly Eijiro nods at the news, like he's excited for him to be gone.

When he leaves for his "trip" Katsuki almost doesn't even bother to kiss Eijiro goodbye.

But Eijiro somehow bullies one from him, right before waving him off and closing the door to their home in his face.

It's only a 15 minute drive to the nearest hotel, but having to wait until night fall seems endless.

Katsuki paces his room like a madman, checking his phone.

His eyes hardly ever leave the family tracking app they installed years ago, and it's almost frustrating to see Eijiro's bubble never leaving the house.

It almost makes Katsuki second guess himself, wonder if maybe he'd actually just worked himself up over nothing.

He's about two second from calling this whole thing off, to text him and say there's been a change of plans and that he'd be home soon. Katsuki even gets as far as to open up the app and then he realizes... He'd been here in the hotel for hours and Eijiro hasn't said a word.

His husband is uncharacteristically silent. Too silent.

Fuck him.

Katsuki was going to the house.

It's just after dark when he arrives to his neighborhood, and from the street he can see the lights are on in his home. At least the app was right about something, Eijiro was definitely home.

Nervously, Katsuki walks up the driveway, trying to be quiet.

He feels like an idiot sneaking into his own home but he needs to find out for himself what Eijiro was up to.

Holding his breath, Katsuki sticks his key into the lock and opens his door. Closing the door behind him, Katsuki's stills as he tries to hear what he can.

Suddenly there's a loud bang and Eijiro yells out, "Oh my god! You're so good!" The next sound he hears is a long drawn out moan followed by a fit of giggles. Giggles that do not belong to his husband.

Katsuki runs into the kitchen, slapping hand against the archway. "HA!" He bellows before pointing a finger at Eijiro. "I KNEW YOU WERE UP TO SOMETHING!"

There's two sets of gasps as two heads whip up to look at him.

Eijiro looks shocked, the other glares.

"Daddy! You aren't supposed to be here!" his son yells at him, pointing a frosting laden wooden spoon in his direction. "Papa," Ryu squeaks out in his little voice turning towards Eijiro, "tell daddy he's being a bad word!"

Eijiro absolutely howls with laughter at that.

Katsuki scoffs and rolls his eyes.

Wiping his eyes, Eijiro looks down at their son who's is standing on a stool at the counter, his bottom lip trembling. Katsuki notices at the same time Eijiro does but he's quicker to scoop him up. As soon as be does, Ryu bursts into tears.

"I just wanted to make daddy a surprise!" He cries.

Eijiro, now glaring over his sons shoulder, makes sure to look at Katsuki as he rubs the little boys back. "I know baby, I know. Shhh."

"He ruined," he wails.

Katsuki can't remember ever feeling so low and his own eyes start prickling at the corner.

"I didn't mean to," he finally chokes out, earning him an angry look from his son who turns his head around to face him. "Can I have a hug? Please? I'm sorry."

Ryu shakes his head and buries his face back into Eijiro chest.

Walking over to him, Katsuki extends his hand and gently pats his son's dark hair. "C'mon can't I just have one teeny little hug?"

And Ryu, who can only stay mad for so long turns his head and sniffles. "Only one because you hurt my feelings."

And God if that doesn't make him feel even worse. Opening up his arms, Eijiro helps transfer Ryu over and Katsuki squeezes him tight.

While still holding him Katsuki begins to cover his little boys face in kisses until Ryu is finally giggling.

"Do you forgive me?"

Ryu pouts and looks over at Eijiro who gives him a little nod and he sighs. "Okay."

When Ryu is asleep and the cake they were practicing making was put away in the fridge, Eijiro properly scolds his husband for being the worst birthday surprise recipient in the world.

Katsuki really really hates surprises but he loves his son and husband more than anything in the world so he promises through gritted teeth that he won't make a fuss about his birthday anymore.

And when he sees his sons face light up when Katsuki is "surprised" by his surprise party that Eijiro begrudgingly let him know about in advance, he thinks that maybe next year he really will play along.