In my opinion there are very little fics where Izuku joins the Vanguard Action Squad like Dabi and Toga without being affiliated with the league beforehand or not being brainwashed. So in order to fix this I present my take on the idea. Enjoy!
"And who are they supposed to be?" Shigaraki Tomura the leader of the league of Villains asked.
Standing in front of him were three people that the leagues info broker, Giran had brought as potential recruits. One looked like a psychopathic blond chick with a big grin on her face. The second was a guy that had purple skin patches stapled all over him, but keeping the style symmetrical and looked like he could care less about being here. The third was about the same age as those UA brats that kept interfering with the leagues plan and had green hair and equally green eyes. Still that didn't help with the fact that the boy looked nervous out of his mind, and was slightly shaking.
"Come now Shigaraki," Giran said lighting a cigarette. "I brought them here for you. Their interested parties looking to join."
Shigaraki glared behind Father as he looked the trio over again.
"Your names!" Shigaraki demanded.
"OOH Me first! Me first!" The blond girl said jumping up and down, and raising her hand in the air. "My names Toga, Toga Himiko! Life's so hard so I want to make it easier to live in. I want to be like Mr. Stainy, I want to kill Mr Stainy. So please let me join!" Toga said as her mouth was wide showing off her canine like teeth.
"I'm currently going by Dabi." The guy with stitches said dully.
"No I want your real names." Shigaraki said looking at Dabi.
"I'll tell you when I feel like it," Dabi said glancing at both of his sides. "And does this organization really have a just cause, because it doesn't seem like it if your letting this Psycho blond and this Shaking Tennis Ball in," Dabi said as Toga fell backwards in mocked pain, and the other person just started fidgeting nervously."In any case I'm going to carry out the Hero Killers will."
Shigaraki was brimming with anger as Dabi continued talking. Sensing the danger Giran excused himself and left before he could get caught in the crossfire that would inevitably ensue.
"I don't like it," Shigaraki said getting up, an aura of blood lust emanating from him. "Everybody is always a buzz Stain this, Stain that," He continued as he stood up from the bar stool he was sitting on, the others in the room sensing the danger. "I hate IT!" Shigaraki said lunging forward with the intent to disintegrate them.
The following events happened nearly instantly. As Shigaraki lunged forward Dabi activated his quirk as blue fire engulfed his hands. Toga slung her arm out to reveal a hidden butterfly knife and thrust it forward. The other person just looked shocked and tried to brace for the pain to come. Kurogiri on the other hand activated his quirk sending Toga's knife into the bar, Shigaraki and Dabi's hands into the air.
Using his quirk to extend his head closer Kurogiri whispered something into Shigaraki's ear. Shigaraki shrugged him off as his hands were freed and shoved past the trio and left. The trio each had different reactions. Toga was acting giddy because she thought she was going to die and got turned on. Dabi was unimpressed by Shigaraki and his childlike demeanor. And the last person still looked shocked but was relieved the danger had been averted.
"My apologies but would it alright if we we're to talk about your recruitment at a later date," Kurogiri said as he returned to his business like gentleman demeanor."Young master just needs to calm down and think some things over. All the recent events have left him confused on himself."
Dabi let out a sigh as he threw his head back in annoyance. "Fine whatever, just give me something to drink right now." Dabi said as he sat down on a couch in the bar.
"Very well,"Kurogiri said as he poured a glass and set it in front of Dabi. "May I get either of you two anything?" Kurogiri asked looking over.
"OHH! I'll take a Bloody Mary!" Toga said as she sat down on a bar stool.
Kurogiri gave a sigh and reluctantly made the 21+ drink for the obviously underage girl. Hey their villains, a lot more worse things than underage drinking they could be doing.
"And you." Kurogiri asked setting the drink down in front of Toga.
"Oh uh... whatever is fine." He said sheepishly stuttering a little bit.
Kurogiri narrowed his eyes at him. He was the same age as the UA kids they had attacked and looked nervous to be here. Further investigation was warranted Kurogiri decided.
"Pardon my asking, but do you really think you can be a villain?" Kurogiri asked as Toga and Dabi looked at the person who accompanied them.
"Well ... kinda." They said trying to not freak out.
"Then may I ask what particular set of skills you have, such as your Quirk or combat expertise." Kurogiri asked as the other person started shaking nervously.
"Well... the thing is," The boy said drawing on before sighing. "I don't have one."
The air stood still in the bar as he said that. Kurogiri was making sure he heard the kid correctly. Him, a child came to the League of Villains to be recruited and was Quirkless. Either he was plain ignorant or had something else that was of use. Then Kurogiri remembered something, how Quirkless were often looked down upon by society and that this child probably experienced that mistreatment.
"I see," Kurogiri said as he thought about his next response. "Any other useful traits or things you can provide?"
The person slightly perked up at that as the moved over to the bar and reached into the bag they brought with them. Pulling out a few notebooks they set them on the bar in front of Kurogiri, who eyed them with curiosity. Particularly what they said on the cover.
'Hero Analysis for the Future, by Izuku Midoriya'
"I know the cover title doesn't really help my case, but I didn't want to have to move them to another one when I could just add more information to them." the now named Izuku said rubbing the back of his head.
Again Kurogiri eyed the books and the child with a now peaked curiosity. While he couldn't undermine Shigaraki and let the three in he could still learn anything useful from them while they were here. So slowly he grabbed the first book he could reach and opened it. Toga tried leaning over the bar counter to see what he was reading but couldn't lean far enough. Kurogiri on the other hand found himself reading a wealth of information.
'Hero names, their Quirks, Combat styles, Strengths and Weaknesses. Quite the analytical mind judging from the detail and organization of the information.' Kurogiri internally said as he read Izuku's notebook. It was a literal goldmine of information on both high level and low level Hero's. It even included a few civilian identities that could be put to later use to catch them off guard.
"Its very..." Kurogiri stumbled on what to say next. "Detailed."
Izuku's eye's lit upon receiving the compliment making Kurogiri think that was a rarity for the child.
"Thank you!" Izuku said bowing his head quickly.
During this Toga and Dabi still eyed Izuku with curiosity. Dabi more so with wanting knowledge on what was in the notebooks since he hadn't bothered to get up and look, and Toga wondering what kind of info it had. Setting the notebook in his hands down Kurogiri poured Izuku a glass of water as he sat down.
"Rather useful information Midoriya," Kurogiri said as he began to polish the empty glasses in the bar. "To gather such knowledge and compile it as you have without a Quirk is rather impressive."
Izuku beamed again as he drank his water. How ironic was it that the Villains were the ones giving him praise before they even really knew him, and that the people who knew him all his life that wanted to be hero's tore him was busy putting his notebooks up that he didn't notice Dabi getting up and sitting next to him.
"Why?" Dabi asked Izuku who looked surprised at the others sudden appearance.
"I d-don't understand." Izuku said looking at the older teen.
"I asked why," Dabi said again. "Why do you want to be a villain."
Izuku fumbled with what to say before Dabi spoke up again.
"Is it for the money, the publicity you could get, or are you just another second rate thug?" Dabi continued listing off answers before Izuku spoke up.
"I want to prove them wrong." Izuku said quietly that Dabi could barely hear it.
"Come again." Dabi asked as Izuku looked at him with an expression that looked foreign on the small freckled face. It was a look of hate, regret, and rage.
"I want to prove them wrong." Izuku said again louder. Now this was getting interesting for him. Kurogiri was ready on standby with his Quirk should another brawl decide to start, but still eyed the child with curiosity that was shared by Toga.
"Prove who wrong?" Dabi asked raising an eyebrow.
Izuku didn't say anything for a few seconds before speaking.
"Everyone! I want to prove everyone wrong that ever looked down on me for being Quirkless," Izuku said growling as images of Bakugo entered his kind, and the years of abuse he endured. "If they said I couldn't become a hero, then why not show them how strong a villain I can be." Izuku finished as hehadn't realized his grip was cracking the glass in his hand, causing blood to trickle out of it.
Dabi smirked at the reveal, a kid like him who was looked down upon deciding to show his strength. That was a rarity nowadays since normally people would just give up when faced with that situation. Maybe he could tolerate the kid after all, that was if Shigaraki decided to accept them.
Which speak of the devil and he shall arrive, as Shigaraki entered the bar with a grin on his face.
"Glad to see the enthusiasm," Shigaraki said catching the others off guard. "You all want to join the League, then your in," Shigaraki continued as the others perked up upon hearing that. "Now then there's a small matter that needs to be taken care of."
"Which would be?" Dabi asked as he drank more from his beverage.
"What's our villain name Izuku Midoriya?" Shigaraki asked grinning.
Izuku answered almost nigh immediately. He had long since decided on a name for him to use, since even if his identity was figured out there was no one to use against him, ,... regrettably. But he was choosing this name for the future purposes, so when he and Bakugo finally meet again he would remember. He would remember that the Quirkless Izuku who he tormented since he was 4 had outdone him. Had beaten him using the name he had given to mock him.
"Deku."
Short chapter yes I know. I am intending for future chapters to be between 3 to 5 thousand words each. I just needed to get the intro out of the way. Also since I know Izuku played roles in canon that directly decided if some characters lived or died, yes All Might has another successor who helped them out so Lida is still alive,and Stain is incarcerated. Just assume canon happened without Izuku.