The day Shizuo met Izaya, he tried to kill him. There was no real reason, he just didn't like him. Whenever someone asked why, he couldn't really answer. When pressured to answer, sometimes he'd say it was the smirk while others he'd simply send that person flying. What Shizuo wanted to be able to say though was that things didn't change much after that afternoon, but the truth was that his already less than peaceful life plummeted into chaos after Shinra had the 'bright' idea of introducing Izaya to him. The pest (the nickname Shizuo gave him because that's exactly what Izaya was) almost immediately sent gangs after him, the many fights he was forced into getting him in trouble both at school and at home.
The nightmare didn't end even after they graduated, Izaya doing everything in his power to ruin Shizuo's life any way he could. Ikebukuro turned into their battlefield, people soon learning to get out of their way if they didn't want to end up as collateral victims to the volatile monster and the dangerous informant. Years went by (almost in the blink of an eye) and Shizuo failed to catch Izaya most of the times, but once in a while he'd get lucky. Their latest fight ended with Izaya getting a bleeding head and a dislocated shoulder, but even with those injuries the pest still succeeded in slicing Shizuo's arm.
Just another day in Ikebukuro, Shizuo thought as he angrily bit down on the cigarette, struggling not to growl the mantra of kill kill kill when Izaya was nowhere in sight. The flea always somehow managed to avoid getting his neck broken, easily slipping through Shizuo's fingers like he was this ethereal thing instead of nothing more than a loathsome insect. "Izaya," Shizuo hissed through gritted teeth as he balled his hands into fists and continued to look for the flea, refusing the give up when there was still a certain stench in the air which he always associated with brown with a hue of red eyes and an annoying smirk.
Shizuo thought it was a shame that Izaya wasn't bleeding more; following a blood trail would've been much easier than having to rely on his instinct to lead him into the right direction as he made his way through side streets and alleyways. Giving his arm a quick look, he felt his ire rise, the cut and the blood soaking it making the shirt unusable. Izaya had destroyed another one of the precious uniforms Shizuo had received from Kasuka, and even though it wasn't the first time (nor would it be the last), he was still seeing red.
"Kill! Kill! Kill!" he started muttering under his breath, not even paying attention to his surroundings as he turned right and entered an alley, his feet leading him inside despite the dangerous-looking group of men standing in the middle and blocking the route. Shizuo expected them to move (after all, he'd made a name of himself, even if not intentionally), but nothing happened as he approached them so he took it upon himself to make way by placing his hands on the shoulders of two of them and pushing the unlucky men to the side, freeing enough space to pass through.
"The hell you think you're doing?" one of them barked and pulled out a knife.
Shizuo only heard half of what the guy was saying, the rest having stopped registering in his mind the moment he caught sight of Izaya's switchblade lying on the ground. Wanting to make sure that it was really the flea's weapon, he moved towards it to pick it up, but one of the man stepped in front of it, knife poised to attack if Shizuo so much as moved an inch. A swift glance around revealed that he'd been surrounded, and since he was in a bit of a hurry, he didn't feel like wasting precious time he could spend tracking Izaya. "You're in my way. Step aside while you can still walk," he warned as he threw the cigarette butt on the ground and crushed it under the sole of his shoe, all the while hoping that he wouldn't have to fight since he wasn't in the mood to deal with yet another gang.
"Wait, he's—" one of them started, but by then it was already too late.
The sound of a bat snapping in half on impact was almost immediately followed by those of anguished screams, resounding throughout the alleyway and mixing with those of bones breaking and bodies hitting the ground. It was over before the guy who had tried to warn the others even had a chance to escape, the terrified-looking man just standing there as the horror of what he had witnessed left him paralyzed with fear. All he could do was watch with eyes wide open as Ikebukuro's beast stomped towards him, the burning fury in Heiwajima Shizuo's eyes turning his knees to jelly. His legs gave out from under him and he fell on his ass, stuttered apologies and begging to be spared by the monster looming over him and cracking his knuckles.
Shizuo didn't normally stop once he got started, but the pathetic sight the man was making, violently trembling and crying like a coward at his feet, made him lower his arms and turn on his heels, choosing to look for the switchblade he assumed was Izaya's instead of breaking the guy's bones. He had to kick a few unconscious bodies out of the way to find it, and he confirmed on closer inspection that it was really the flea's knife, the same one the insect had used to ruin yet another one of his shirts.
Growling low in his throat, he pushed the blade back into place and pocketed it, all the while fighting the impulse to crush it in the palm of his hand. He had no doubts that it would piss off the flea to know that his precious switchblade had ended up in enemy hands, and Shizuo had every intention of letting Izaya know what happened to it as soon as he found the bastard; after taking care of his injuries. His head was bleeding pretty badly and there was a deep cut gushing blood on the left side of his stomach, not to mention the gash in his arm that had tinted his sleeve crimson.
The wounds didn't really bother him that much, but he knew better than to ignore them after that one time when he'd nearly bled to death (or so he recalled Shinra saying). While he'd caused a lot of trouble for his family over the years, he doubted that any of them would want to see him dead. Letting out a frustrated sigh, he headed towards Shinra's apartment, his hand itching to crush to smithereens the switchblade he was hiding in his pocket.
It was dark outside by the time he reached the underground doctor's apartment, feeling cold, hungry and irritated after the extremely shitty day he ended up having because of Izaya. He hoped to relax a bit and talk to Celty while Shinra patched him up, but that went down the drain when he stopped in front of the door and he realized that the whole place reeked of flea.
A vein popped beneath the skin of his forehead and his hands shot forward, strong arms tearing the door from its hinges and raising it in the air as he made his way inside and towards the living room. He didn't even notice Celty until she was right in front of him (as though she'd suddenly materialized out of thin air), blind to everything around him the moment his eyes locked with brown-red irises and every muscle in his body demanded to kill kill kill Izaya once and for all. He should've realized sooner that the louse would come to Shinra to patch him up, and he was so pissed that he couldn't even hear what the doctor was saying.
Ignoring the murderous-looking blond, Shinra turned to Izaya, eyes wide in surprise. "You don't expect me to believe you did all this!" he stated incredulously, leaving Celty to deal with his former classmate who was still holding the door above his head and snarling at the raven sitting calmly in the armchair.
Rolling his eyes, Izaya turned to Shinra, deciding to answer the doctor's question as thanks for patching him up. "I only lay claim to the gash on his arm," Izaya clarified, sinking further into the armchair even as the brute was trying to get past Celty to break his neck or possibly rip his head off. The beast roared a moment later and Izaya turned to Shizuo, but the animalistic sound was followed by absolute silence that lasted for a good while until the blond sneered, placed the door against the wall and turned to him with an unnerving smirk plastered over that idiotic face.
"Flea, guess what I found earlier?" Shizuo asked, shoving a hand into the pocket of his pants.