People are not born equal, the world is often cruel to most and Midoriya Izuku was not an exception.
He had been playing with Bakugou Katsuki and his friends when his quirk manifested, they were in the woods and crossing a fallen tree log that had been turned into a makeshift bridge to cross a river below them. "Kacchan" as Izuku would call him was popping off small explosions, his quirk had already manifested and he let everyone know how strong it was, and how strong he was, even if he got physical to show it.
Whilst crossing the tree log Kacchan had lost his footing and fell down into the river, no one tried to save him, not even his friend who had wings as a quirk bothered helping, instead he just said that "Bakugou was strong so he'll be alright". So Izuku being Izuku slid down the side of the dirt and ran into the river to see if Kacchan was alright, he extended a hand and asked if Kacchan was alright, this angered Kacchan who went to hit his hand away, but instead of hitting his hand away Izuku flickered away back to the tree log bridge and then back to where Bakugou was, he started flickering all over the place and he couldn't stop.
At first Bakugou Katsuki had been angry at Midoriya Izuku, he didn't even have a quirk yet he would always rush to him to make sure he was alright, and once again he had done this, rushing to him when he fell into the river to make sure he was alright, he wish he would take a note from his other lackeys and know that he's strong enough to handle himself, he was the one with the quirk after all, whilst "Deku" hadn't even gotten his yet. So when he saw that hand reach out to him and heard that voice ask if he was all right he was angry, so he went to hit the hand away, only for his hand not to hit a hand at all and Deku was suddenly back to the tree log bridge, he was only there for a second before he was back in front of him.
After witnessing this Bakugou Katsuki was excited, that stupid Deku finally had a quirk! This meant he could beat him down without it looking unfair to others! From what it looked like Deku had some sort of teleporting quirk, since he was flickering everywhere, all this meant was that to beat up that stupid Deku he just had to catch him. "Hey Deku, stop teleporting around!" is what he said to Deku at first, when Deku didn't respond he got impatient, "Stupid Deku! Stop messing around!" he was getting irritated, no one ignores him, so when Deku appeared in front of him again he went to grab him, only for his hand to go through his arm, when this happened his finally saw Midoriya Izuku's face, and it wasn't a face that looked excited at manifesting a quirk, it was a face full of fear. Bakugou Katsuki was no longer excited or mad, he was worried.
"Hey! Wingfreak! Go find a hero or something! Stupid Deku can't control his quirk! I can't even grab him to stop him from teleporting about!"
The aforementioned wingfreak who looked slightly insulted at the name he had been giving agreed and flew out of the forest, hopefully to find an adult leaving Bakugou and the rest of his squad there with an out of control Deku.
What felt like a century to Deku was actually only a few minutes, he had only gone to help his friend when he suddenly started going out of control, and unable to interact with anything, he could hear Kacchan but couldn't make out what he was saying, when Kacchan tried to grab him he saw his hand pass through him, and this put Izuku into an even bigger panic, a few seconds later he saw the boy with the wings quirk fly away, it was hard to keep track of where people were since he was constantly moving around.
Aizawa Shota hated hero work during the day, so he decided to sit down in a park and take a quick break, catch his breath, people were annoying after all. So when he spots a kid with wings flying about in a hurry he thought about not giving the kid a lecture about using his quirk recklessly like that in public, technically you weren't supposed to use your quirk at all but this was a kid so he didn't think too much about it, however, he is a hero so he should teach kids what not to do, so he calls out to the kid, "Hey Kid flying over there! Stop being so reckless you might fly into someone!" The kid turns and looks at him, he saw a flash of relief on the kids face as he flew over to him, then the winged kid started talking at 100 miles per hour, and he couldn't make a word out, "Slow down, I can't make out a word your saying." After catching his breath the kid said what he was saying in a still quick, but actually hearable sentence, "One of our friends just manifested their quirk or something and they can't control it, they keep teleporting about and we can't grab them!" Aizawa sighed, he came here to relax but heroes can't have everything, "Show me the way."
When Aizawa arrived he saw a kid flickering around, he could tell the kid was panicking, it's a good job I'm here, I can sort this out easily with my quirk, Aizawa thought as he activated his quirk looking at the kid who was on his hands and knees in the river crying, the blonde kid who was trying to catch the kid grabbed the kid and let out a sigh of relief. Aizawa walked down to the kid and said to him, "I'm going to take this kid to the hospital, do you know his parents?" The blonde nodded, "Okay, I want you to notify them that he's at Musutafu Hospital, and that his quirk has manifested, hurry up now." The blonde nodded once more and called out to his friends and they started to run out of the forest. Aizawa looked down towards the green haired kid, "What's your name? Deep breaths, and then tell me." he asked, the kid was obviously still panicking, and he needed to calm him down, the kid did what he said and took a few deep breaths, "M-Midoriya Izuku", "Alright Izuku, I'm going to be taking you to the hospital okay, then we'll find out what your quirk is and you'll learn to control it." Izuku nodded and stood up, Aizawa may seem heartless but he wasn't, he picked up the kid in a piggyback, once he had the kid on his back he introduced himself, "I'm Eraserhead, nice to meet you". Then he proceeded towards the hospital.
BLINK TOWARDS THE HOSPITAL
Aizawa, Izuku and Izuku's mother were all sat in a room with a quirk specialist, Aizawa stayed as the moment he deactivated his quirk the kid started going out of control again, I'm going to be seeing a lot of this kid he thinks to himself.
The quirk specialist looked towards the child's mother and spoke, "So, your son's quirk, it's peculiar indeed, it basically turns him into a living ghost, without Eraserhead here to erase it he would probably disappear and reappear randomly, sometimes it could be for a few seconds, other times it could be up to a few hours, maybe even days."
Aizawa could see the horror appear on the child's mother, it was understandable, no one would want a quirk like that, the kid suddenly spoke up, "C-Can I be a H-Hero? With this quirk?", Aizawa had no idea if the kid could even live a normal life anymore, a hero seemed to be far off, the mother kneeled down infront of her child and hugged him, tears streaming down her face, "I'm sorry Izuku" is all she could manage to say.
The quirk specialist dragged Aizawa over to a corner, his eyes were also watering, not because of the kid, because of his quirk, he had seen people's lives end before, whilst it sad this kid may not be able to live a normal life, he still has one. The quirk specialist said to him "We're going to need a name for his quirk, usually we ask the children or parents what they want to name the quirk if it's a quirk that doesn't exist, I don't think that's the best idea right now though, so I'll ask you." Aizawa wasn't the best with names, he didn't even create his own hero name, that honor goes to the one and only Present Mic, so thinking of a quirk name on the spot was hard, "How about, Slipstream? He slips in and out of existence, it makes sense, in a way I guess" the specialist just nodded, "We'll go with that then".
And with that, a new quirk was added to the quirk registry,
Slipstream.