AN: First I wanted to make a fic where Izuku had an evil alternate personality. Then I wanted to write a pet shop fic. Then I realized my own stupidity and did both at the same time.

Izuku got up from the ground, only to be find himself once again at the receiving end of a kick. Ever since his peers had discovered the boy was quirkless, he hadn't gone one day without constant teasing. He looked up to the face of his bully, and saw the same angry eyes he feared day after day. Even though he was on his own this time, Izuku still feared him nonetheless.

"Kacchan… please don't-" His tired cries go interrupted by a voice in his head, one that didn't seem to belong to him. 'Let me take over for now, it's my turn to play!

He felt his entire body go numb as he lost all control and was left as a spectator. Instead of trying to get up another time, he saw on the corner of his eye his hand moving towards a shard of glass on the ground as adrenaline coursed through his veins. He tried opening his mouth to warn the unaware bully, but no matter how much he struggled no words came out.'Kacchan… !' He desperately thought.

He realized his fight to regain control was for nothing when he felt the shard of glass dig into his hand as his body thrusted it into the bully's direction just as he was preparing a punch. The glass cut the boy's cheek in a straight line, and as blood started pouring out of the wound Izuku managed to drop the sharp object,feeling the voice in his head fade into the background.

"K-Kacchan! I-I'm sorry, I didn't mean it!" He cried, but quickly backed away into the ground when he saw his bully's fury increase tenfold as tears started to form in his eyes.

Katsuki in turn felt more anger than he had ever felt in his entire life. Fueled by the pain his cut gave him, the boy concluded his punch with an explosion, which fiercely hit his victim's face, leaving a burn mark in the place it hit as Izuku was pushed back by the force. He quickly got up and ran home in shame, crying not only for his burn but also for hurting his childhood friend.

"Who are you?" He asked the voice in his head, who he deemed responsible for his current state.

'You mean you've never noticed me? I've been here this whole time! Tell you what, call me Izaku! It would be pretty confusing if we were both called Izuku, and I don't want to have the same name as a loser like you.' Izuku fell back startled by the unexpected response.

"Don't say that! Besides, why did you hurt Kacchan? He felt Izaku laugh loudly at his last question, as if he'd been told a joke.

'I cut him because he's a little shit, what else?! You think I'm just gonna sit there and watch our body get beat up?'

'What do you mean our body? This is my body, and it's always been!'

'Just because I've never spoken up till' today doesn't mean this body's only yours! You're gonna have to learn how to share, or we won't get along very well...'

4 years later

Ever since Izaku had given a scar to his childhood bully, he'd rarely received other threats, and instead became someone people feared, as everyone around him imagined the boy as violent and unstable, rumors started by Katsuki.

Even though he dreaded the times Izaku took control of his body, which happened at least once a day, Izuku knew he couldn't force him back. He had tried a few times, all with disastrous consequences. In his eleventh birthday, after a week of being denied control, Izaku managed to take hold of a knife and dig it into his arm. One year later, under the same circumstances he successfully set fire to the couch, which left the boy in the hospital for a week.

Being fourteen now, he had started to get used to Izaku's daily possessions. Today, he walked alone from school through a path he knew people avoided. Izaku liked to collect empty bottles, which he kept under his bed for 'emergency reasons'. He crouched to check on a fallen one when he felt someone creeping up behind him. As the figure got closer, Izaku grabbed the bottle and quickly swerved it into their direction, however, the bottle passed right through its body. In front of him stood a figure which seemed to be made of a dark green slime, with bulging eyes that screamed 'insanity'.

"What do you want?" The boy casually asked, retrieving his bottle from inside the man. However, before he could answer, All Might fell to the ground behind him, defeating the villain in the span of a single catch phrase.

Overwhelmed by the sight of his childhood hero, Izuku managed to take back control. " A-All Might! Can you give me an autograph?" He quickly stuttered, trembling from excitement.

"Of course, young boy!" He cheered, scribbling in Izuku's notebook. He gestured his hand to return it, setting his eyes on the boy's bottle. "Can you lend me that bottle you're holding?"

"S-sure!" He chirped enthusiastically, handing over the object, which the hero used to trap the villain. Suddenly, Izaku grasped the control back and angrily took the bottom from All Might's hand, who looked at him curiously.

"Be sure to dispose of that in the local police station! Farewell!" He swiftly jumped out of view, prompting Izaku to look scornfully at the bottle in his hands. Regardless of Izuku's struggles, the boy removed the lid, setting free the surprised looking villain.

"Thanks kid, I owe you one!" He croaked, slithering away. Izaku smiled. 'How can you like that pretentious jackass?'

"He's a hero! He saved us from that villain guy!"

'Sorry to disappoint you, but heroes are only in it for the money. Besides, that guy actually owes us now! He can be useful instead of just rotting in a jail cell!' Izaku answered as he got into their home. The boy lazily fell on the couch and turned on the TV, returning control to Izuku. The image he saw made him hold back tears, while Izaku laughed madly inside.

Katsuki Bakugou. Being attacked by the same villain he had just set free. 'See! I told you he'd be useful!' He cackled. While Izuku had grown to just ignore Bakugou, Izaku had always felt deep hatred for the bully.

'I-Izaku! This is our fault! Kacchan could die! All Might would hate me! I'd never get into UA! oh my-'

"CALM DOWN! First of all, All Might probably doesn't even remember our face. Secondly, we're not getting into UA either way. We're quirkless, remember? All those little shits look down on us."

'I've been studying really hard! If we use your reflexes on the physical test, we could make it!' Izuku concluded, even though he knew Izaku would never want to go to UA.

As Katsuki fainted still in the villain's hold, the spectating heroes ran into action and rescued the unconscious boy. Later, Izuku would learn Katsuki spent nearly a week in the hospital undoing the damage the villain had done. The guilt took a long time to go away.

9 Months Later

Izaku charged a slab of metal into the robot's neck, destroying it in a small explosion. After nearly two thirds of the exam, he had finally managed to take down a robot. As he exited the alleyway he came face to face with a giant robot, destroying everything in its path, which currently included a fallen girl. 'Izaku! We have to save her! Run!'

"Hell no! That's a 0-pointer, it's not my fault she's that careless!" He ran back and ignored the girl, as he knew their time was running short. As the buzzer rang notifying the end of the exam, they could hear the faint screams coming from the robot's direction, as Izaku simply kept walking towards the door. 'What did I tell you? People like us could never get in. We're seen as inferior, and this exam is just another reminder of that…' Although Izuku showed no expression, he agreed. There was no way someone quirkless like him could possibly pass the physical exam. His mother was right after all…

Izaku arrived home with a grim look on his face. His mother saw the answer to her questions written in his expression, so she just walked up to him and hugged him. "Izaku, or Izuku, both of you. I'm proud of you two, you clearly did your best!" She cried into his shoulder and Izuku, having taken control, cried back into hers.

After an evening of moral support from his mother, an unexpected suggestion came. "Since you're going to a lighter school next year, why don't you try to get a job at Masai-san's pet shop? She's an old family friend, and she's always saying they need someone to look after the animals."

Izuku looked at her with mild shock, but laughed at the thought of working with animals, and from what he heard of this pet shop, some even had quirks. "I'll think about it, mom." He walked to his room and lay on the bed, more comfortable with having failed the exam.

'Heh, I think working with animals could actually be fun. At least animals like you for what you are, not what you can do…'

"Go to sleep Izaku, for our sake."

"Hmph, fine." He reluctantly agreed, and that night they slept better than they had in a long time.