His shocked brain just told him that those were the bad guys, without any real proof or reason, and ordered his limbs to move, while he felt like he wasn't even really part of this moment, as if this was someone else's body moving towards what seemed like certain death and he was merely watching.
He barely registered a few of the dark figures going down, others backing away uncertainly, as he watched an ominously glinting blade soar through the air, stabbing seemingly randomly, while the knife's wielder moved fluently, almost like he was performing some kind of war dance.
Feeling his heart throb within his throat, he tasted bitter recognition on his tongue when he realized that he had seen someone move like this before. Elegant, graceful and utterly deadly.
On impulse, he almost joined the mob of creatures in trying to beat the dark haired man up, but upon getting closer to him, he not only noticed that the flea was seriously struggling not to take too much damage, something Shizuo had never gotten to witness, but he was also noticed by the grunting, screeching beings, their menacingly glowing eyes focusing on him in a way that made fear snap through his body as if he had been struck by lighting.
Adrenaline came rushing through his veins and he pulled his arm back and punched with more ferocity than even when the flea was his target. His life was in danger and therefore his body reacted.
Not that his life wasn't in danger when Izaya pulled out his deceptively small, yet very sharp knife, but he was usedto the flea threatening him with sharp, pointy object. He wasn't used to random people attacking him without any reason.
His fist was almost like a bowling ball, as it smashed into the mass of beings and knocked down most of them, while he saw from the corners of his eyes that the flea was doing his best at fighting the creatures, doing an amazing job for someone who didn't have super human strength, although Shizuo knew from rather painful experience that Izaya wasn't as weak as his fragile built had first led him to believe.
They fought, until their breathing had turned heavy and their clothes were soaked with sweat and splatters of blood, until their muscles burned from the effort and their necks hurt from constantly looking behind them to make sure those things wouldn't sneak up on them.
Those things just kept coming and coming, and for each one they managed to take down, at least 2 new ones ran towards them to try to kill them off with their bare claw like hands.
Shizuo almost yelled in surprise when something solid and warm bumped into his back and a foreign mop of hair tickled his neck. Turning his head abruptly, he was surprised, and slightly disgusted, to realize that the flea was barely able to stand and was trying to keep himself upright by leaning his back against Shizuo's.
"Flea, what are –" He punched a hoody clad creature in the face and felt slightly nauseous from the feeling of bones breaking beneath his knuckles.
From behind him, he heard the louse breathing heavily, while still managing to cut up some of the creatures and the debt collector realized, that this was actually the most efficient way of making sure he wouldn't be attacked from behind. It was a sickening thought none the less to think that Orihara Izaya of all people, was protecting his back.
There was hardly any time to ponder about how strangely right it actually felt to cooperate with the flea for once, and how efficient they seemed to be together. Slowly, the crowd cleared, piles of unconscious – maybe dead – beings surrounding them.
A hand grabbed hold of his arm and yanked on his ripped shirt harshly and he raised his fist, fully expecting to see another half rotten face glaring at him and stopped his punch just in time to not hit the louse in the sweaty, extremely pale face.
"Let's go!" The informant yelled and ran towards one of the smaller alleys, blindly rattling on locked doors, until he found one that was unlocked and the two of them stumbled into what looked like an abandoned storage room.