Duke Thomas prides himself on knowing lots of things. He knows how to take care of himself. He knows how to lead a group. He knows how to punch someone. These days he knows how to hack a computer. How to pick any lock. How to properly punch someone. In twenty different ways. There is one thing he doesn't know though, and that's what it's like to have siblings.
Because, sure, Batman's proteges work together like a well-oiled machine, Duke has seen this first-hand. But what Bruce forgot to tell him is that outside their uniforms, his new family members are one hundred percent pure unadulterated siblings.
1.
It starts off as a friendly sparring session. Duke is in the cave, working on a case for Tim who's sick in bed (the others shrugged when he mentioned that; Duke feels like there's more to it) papers scattered all around him. He's been trying his best to make sense of Tim's chicken scrawl to a background of steadily increasing insults. Jason and Damian have been at it on the sparring mats for the past half hour and at first they were just taunting each other in between well placed punches and kicks. By now their language is evolving so colourfully that Duke can't help but cringe every now and then. He's about to gather up all his casework and move to the study upstairs to work in peace when it happens.
The drop that makes the cup run over. The straw that breaks the camels back. Two emotional hot-heads who have just pushed each others buttons a bit too much.
"If you fight like this it's no wonder Father let you DIE!"
A silence falls over the cave. Duke turns around, his arms full of paper, just in time to see Jason's face go scarily blank. And oh he knows that look.
"So you still think you're so much better than us, huh?", Jason snarls, wiping sweat from his face. He shakes out his bangs before raising his fists again, all quiet calm and determination, "Then prove it, ya fucking brat."
Damian, to his credit, holds out longer than Duke expects.
Jason lets Damian come to him, blocking several jabs and punches, letting a few connect to lure Damian into a false sense of victory. He waits till Damian has to flip back to catch his breath for a second before going on the offense, throwing out wild, savage punches and kicks, forcing Damian to resort to acrobatics to avoid him.
Duke knows that Damian is able to take down opponents that are bigger than him. He has to, because almost everyone is bigger than him. But Jason is bigger and stronger. He's the tallest and the heaviest of all the Wayne kids; Duke is pretty sure he weighs more than Bruce even.
Damian jumps out of the way of another sweeping kick and lands in a crouch, breathing hard now. Duke watches him, sees him narrowing his eyes, setting his jaw. And then the kid is moving again, ducking under Jason's left hook, launching himself in the air to deliver a roundhouse kick to the face. And for a fraction of a second Duke believes that the kid is going to beat Jason. Then all of sudden Jason has Damian's outstretched leg in an iron grip and throws him to the floor with so much force Duke sucks in a breath. Damian's shoulder hits the mats, and he manages to turn his rough landing into a roll, but when he raises his head up Jason's fist is waiting for him.
Crack.
The sound reverberates through the cave. Duke almost drops his papers, ready to break up the brothers if he has to. A second passes. Then Damian's hands fly to his face and a groan escapes from the kid's lips. Blood starts streaming from underneath his fingers, dripping from his chin onto his t-shirt.
Uh oh, Duke thinks.
"Fuck." Jason says and drops to his knees, trying to pull away his brother's hands to survey the damage, "Shit. I'm sorry!"
Damian is not having it, slapping Jason's hand away with his left while trying to pinch the bridge his nose with his right. It's not helping. Blood splatters on the mats, making the whole scene only look more dramatic.
"You broke my fucking nose!" Damian yells angrily and Duke sees Jason throw nervous looks at the stairs to the manor.
"Calm down, Dami," Jason tries to shush him, "I didn't even hit you that hard."
"You BROKE my nose!" Damian repeats, the redness in his face not just coming from the blood anymore, "I'll be benched for a week!"
"Shut up. Just sh.."
Duke is pretty sure that clamping a hand over your little assassin brother's mouth is a bad idea, but clearly Jason fears something else more than being bitten by a demon child. Duke realises this might be the right time to bail, before he gets dragged into it.
"What the hell is going on here!"
As Duke turns around, Bruce is suddenly there on the stairs, looking pissed beyond measure. Duke watches as the man's cool blue eyes take in the sweaty mats, the blood on Damian's face and Jason's stricken expression.
"We were just sparring," Jason starts, a nervous quality in his voice that Duke doesn't hear often from him and Duke takes that as his que to make like a tree and leave, Tim's casework be dammed. He holds his arms up in surrender as he passes Bruce, muttering "I had nothing to do with this," and takes the last few steps two at the time. The last thing he hears, is Bruce growling about the 'no injuries while sparring' rule before he shuts the grandfather clock behind him. He takes a deep breath, rolling his shoulders then sets of in search of Alfred. If what he just observed can be considered a normal sibling experience, he needs to know how to prepare.