So let me being with his quirk.

Quirk-author while having anything to write on and with he can pick what happens.

Also when active it effects others around him.

Example-if he was failing a class he could either write to make him self the smartest person alive or write the "teacher when grading put the wrong test score for izuku, and went to change it" now that means his teacher actually thinks he mess up and is now fixing the problem. Now let get on with the story

We began with 5 year old izuku playing with his friends and sharing his allmight toys. When he then notice that bakugou hands started to do small explosions and all the kids were shock seeing him awakening his quirk, teachers came and were a little surprise about this kid power. And as normal bakugou get to cocky and thinking he the best and same thing happen for a week with other students, until izuku mother thinks it time for him to get him check for a quirk

The doctor(couldn't be me)

Doctor- well man it appears your son is quirkless.

Inko- no that can't be true all the other kids have signs of showing a quirk. Can you do some more test?!

Doctor- i can try but it useless.

All this happing izuku is just dead inside

Two hours later

Doctor "well ma'am um,well he doeshaveaquirk" izuku "WHAT REALLY!?!" Inko "HE DOES?!? I KNEW IT!" Doctor "turns out your son has one strong quirk! May be stronger than allmight or anyone." Inko well can you tell us what it is" Doctor " well what we decided to call it is writer,giving anything he writes come true. ANYTHING!". Inko " you hear that izuku you have a quirk"

Back home leaving the ice cream shop for a snack

"So izuku do you want to play hero!?" Inko said with a small allmight smile. "nah, not right now mommy, I want to try out my quirk so i can show it at school." this weirded out inko, because he never said no to that. "Ok you can test out your quirk sweetie" she said it like, her friend said they couldn't come to her birthday party. izuku now in his room with the door lock and thinking of what he should do "at this point i can become the best hero" izuku says after writing a page of what is going to happen tomorrow.

School(fucking hate being here)

"So today class is show and tell so let see who wants to go first?" Everyone raising their hand. The pre K teacher face was a little worried but pretending it was a hard choice. "Hmm who should i pick" seeing shock that izuku was actually raising his hand "izuku, why don't you share today." yes izuku said out loud. "Ok so today i-" "showing off your allmight toys" bakugou said out loud, getting respect from his lackeys. "Bakugou don't talk when someone is sharing" bakugou looking to the side saying ok. " continue izuku" izuku getting his confident back "ok today am showing my Quirk which allows me to do anything, watch!" izuku somehow starts floating in that air and having one side making a fire ball and the other electricity running down his arm. Everyone in shock seeing izuku showing off 3 quirks! "Omg" bakugou says being a little sad, thinking he was the best but when seeing deku weak deku with 3 quirks!, he started to feel angry thinking he was just a Obstacle he need to break to be the number 1 Hero.

Seven years later

Izuku is now muscular,handsome and well dressed, because of his quirk setting in his classroom with the same people in pre school. "So class today were be planning for our future" the whole class sighs " Who am I kidding, yal all want to be heros right!. So let go to the track to use your quirks" everyone happy showing off their quirk "now remember school rules forbid using your quirk inside. So let see what school you guys can sign up" a blond boy stands "Don't group me up with these losers teach" bakugou said making everyone mad and talking back "shut up extras i fight you all!" this with a evil grin "So bakugou you register for UA, and having a good score on their test" everyone shock hearing the teacher say UA the hardest school to enter, having only 3% of people enter only the strongest can get in. "Oh! Izuku you also wanted to go to UA" now all boys looking at deku and the girls lust in their eyes looking at deku. "Yes, i do want to go to UA" everyone silent until a blond boi stands up "you izuku want to go to UA, Ha don't make me laugh your quirk may be strong but not like mine, both strong and flashy" Izuku Releasing small amount blood lust at bakugou, "so a fight to want tough guy?!" everyone not knowing what to do but stay still fearing for their lives. "Hey, quit it you two or i have both of you suspended from school!" uh bakugou went seeing this could messing him up and his hero career.

3 hours after school

izuku after all that in school left going to a store buying so snacks, but not having enough money he writes on his money saying "when walking down the street izuku would find 100 yen in a dirty book" 1 min past walking finding the 100 yen and buying his snacks. After some time he chooses to walk down a tunnel making it quicker for him to go home before his mother starts to worry about him. So he goes walking munching on his snacks not noticing a green goup falling behind him. Then before even attacking the boy the green sludge was frozen by a pillar of ice not knowing what just happen izuku turns around and says " wow i really was about to get attack by some green slime if i walk down, well i guess it doesn't matter" then a man appears at the other end saying "NEVER FEAR BECAUSE I AM- oh it seems my work was done, You boy was this your quirk?" izuku going a little fanboy over seeing allmight " well yes but like no?" Allmight confuse about what he just heard " isn't your quirk ice?" izuku look at him then back at the sludge villain trying to escape "could we talk in secret" after writing the trap the sludge with a glass dome, appearing in front of allmight shock seeing a glass dome forming around the sludge and giving it to allmight. "Well Thank You Boy,i just forgot you haven't told me your name and now we can talk in secret" allmight saying fast before his timer hits, izuku explains what his quirk is and what it can do. Allmight surprise how this young man have a powerful quirk thinking if was train he could be the best hero that ever lived, no not that even count in allmight head ( he be the best hero forever with his quirk. "Well boy i fear i must go farewell young man" allmight making a shock wave form his jump izuku just waving bye, now walking home going past a Alley where he see bakugou and his "friends" hanging out, so he continue his way home.

Izuku not training before UA entrance exam only in a few hours

"Izuku wait!" stopping izuku before reaching the door (inko can be the skinny lady cause izuku quirk wrote that her life is a good one and that they are loaded with cash but still live in a apartment cause why not but inko going to be the chubby one cause she cute like that) "Am so glad that you made it this far with your quirk and am very proud of you izuku" "thanks mom" closing the door only seeing a beam of light outside (this is what wrote to be really happy and not to be stress). As izuku walk writing what going to happen making sure he gets the highest score in both exams and battle, he also starts noticing everyone was looking at him seeing he fell from the sky making the ground shake and writing in his book(he jumped to not be late) the whole time as that just happened. When he sat down he noticed the yellow man didn't have a mic wondering how he would be able to talk to everyone until he heard him say hello. This made everyone cover their ears, this answer his question, STUFF BEING TALK ABOUT then out of nowhere a blue hair boy stood and said how their was a error on the paper about something and how it was wrong for UA to mess something like that up, but President mic just said because the last one count for 0 points and should be avoided for time sake, this made the boy quite and sat down

President Mic " let get to the battle field" everyone starts to walk and get ready to fight until they see the green boy with normal clothes and a notebook, thinking this boy must think he better than everyone. This for some reason angers the blue hair boy (aka lida) going straight toward him and saying things to izuku about how he should be more ready and take this more seriously izuku, matching face to face with lida saying he should focus on the city than him " 3 2 WHAT ARE YOU WAITING IN A REAL BATTLE THERE IS NO COUNT DOWN"

Here is where the story end for now. Now am going to explain why before fighting the sludge ge was trap, well when he writes it changes the future so the thing he wrote on tells him the effect of what going to happen. like about when he was at a standstill with bakugou he said he wanted to relieve stress so the out was the sludge. And allmight can be heal back to him old self or make him stronger also he would not ofa cause he to powerful and i don't know if i want him to have one girl or a whole haerm i don't know just comment