Ok this is a story I really was passionate about and even started to personally write. Sadly though I have had to many troubles in my life and not enough time to write it.
In this story izuku is the son of all for one and inherits part of all for one's quirk. the part he inherited is small and only allows him to store and use any quirk but cannot take them himself. the part also has a secondary part that all for one doesnt have that lets him merge quirks that he possesses such as a fire breath and and a body that can ingnite will merge evolve or mutate to become stronger. this happens subconsciously but and can be forced as well
In my story I made izuku a op character. he was identified as quirkless at 5 but that was a lie and the doctor that diagnosed him was actually working for all for one that was looking for izuku mom but instead found izuku. A Year later All for one shows up and kills inko and takes izuku and tortures him to become his successor. in the process he learns of izuku quirk and how it works. He then proceeds to give many quirks to izuku to make him even stronger than all might.
Here is a list of quirks I gave him
* gods body a plethora of body enhancing quirks making his body almost invincible. some of these quirks include super strength,speed,regeneration and shock absorption. there quite literally was hundreds more that just merged to create this one mega quirk.
*Gods mind the same as gods body but based around mental quirks. Things like telekinesis, perfect memory, telepathy and once again hundreds more merged to create a hyper intelligent person immune to anything involving the mind.
In the rest of the quirks I based on other fanfic ideas I had.
* Seven deadly sins animals transformation. let's him transform into a hybrid animal between each of the sins animals. (lion pride) goat lust)bear sloth) snake envy) dragon wrath) fox greed) boar gluttony) there are variations for each of these if you wish to uses a different animal bu generally these are the ones used
*I also added many other abilities based on games and t.v such as blinking from tracer. and elemental bending based off I've avatar and many other small quirks that you can choose.
please do this one justice as it was one of my favorites. also no boy love. no offense but I don't like it personally. if you could make the pairing ochoko please do.