Their partnership had been complicated from the start, and it went on that way, none of them really did want to make a conscious effort to adjust to the other and their teamwork was terrible.
After a few months however things started to get better, they were more or less used to be around each other, Barnaby learnt how to make up for Tiger's weakness, Tiger let Barnaby make a lot of arrests he could have made by himself, damage fines had been reduced, they talked more together, even ate lunch everyday together.

And so Barnaby wasn't even surprised when one day his partner came to him asking about his birthday.
"Bunny! I heard it's your birthday soon and I heard you never celebrate, so this year, we're definitely going to!"
"Who told you that? No, nevermind, I don't care. And no we won't celebrate"
"We most definitely will. I don't let you have any say on the matter"
"You're starting to talk like an adult, I'm almost proud of you"
"Stop trying to change the subject, I'll be coming to your place and I'll take drinks along!"
Barnaby sighed, he just knew that when the brat had an idea, there was nothing he could do against it "Fine, fine, do what you want. I can't promise I'll be there though"
"You most definitely will! You're looking forward to it but don't want to admit it!"
"Am not"

They were at their desk doing paperwork when their call bands went on, in a timed and organized ballet they stood up and ran to Saitou's lab to get ready, only to be told that they didn't have the time to get their armors and that they'll have to do without.
It's only once they were arrived on the scene that they finally got an explanation, courtesy of their producer
"Bonjour, Heroes"
This sentence always made Barnaby cringe but he never said anything, Agnès was terrifying once angered, he has seen it on his partner and he definitely didn't want to bring her attention on him.
"Today's problem is Lunatic, the goal is to arrest him so here's the plan. We're going to launch a surprise attack, one by one, Tiger and Barnaby you're starting!"
"Yes!" they both answered together in unison

Something was definitely not normal. Lunatic wasn't moving, it wasn't something he usually did, he would have been caught already otherwise
"Good evening heroes, I have been waiting for you"
"What for?"
"To get rid of you"
And then everything happened much too fast, Barnaby barely had the time to register what happened that his partner was laying in front of him. He was going to be okay right? He definitely wasn't dead, right, right?
Ignoring Agnès' scream of "Go Dragon Kid!", ignoring Lunatic, he ran to his partner's form on the floor, relieved to hear a faint "Bunny, I'm so glad you're fine" out of his lips, "You're a damned idiot brat"
He was about to cry, he couldn't cry, not in front of him. He didn't wait for medics to make their way there, he didn't have the time to wait, he didn't want to waste a single second and so he carried his partner in his arms, taking him to the ambulance, going with him to the hospital, waiting until he was finally able to see him.

He was sleeping when he was finally allowed to see him and so he went home. Once there though he couldn't sleep, no matter what he tried he couldn't sleep.
And so he sighed and put clothes back on again and went back to the hospital.
Using his fame as a hero he made his way to Tiger's room, happy to see he was awake, happy to see the surprise in his eyes and the smile on his lips, happy that he was alive.
"Bunny! Such a nice surprise! What are you doing there at this time of the night? Missed me too much?"
"Well, I promised to spend my birthday with you and I don't know when you'll be discharged, so I came"
"We can't really celebrate though"
"We'll just celebrate your release from the hospital!"
"Sounds like a plan!"
"Good"

Without really thinking about it he took the hand of his partner in his, surprising himself at the gesture, getting even more surprised when the hand stayed there, he squeezed lightly, "Thank you"
"Thank you? For what?"
"You protected me, you didn't have to do that, I wouldn't have died with my powers activated"
"I know. But you're my partner I don't want you to be hurt"
"I don't want you to be hurt either"
He ran a hand in his hair, grinning sheepishly "Well, I couldn't really help it, my body moved on its own"
"Still, thank you, thanks a lot Kotetsu"

"Wait, did you call me by my name?"
"Just shut up and sleep"