Warning! This My Hero Academia article covers current major events from both the anime and manga!
When My Hero Academia's Shie Hassaikai arc came to an end with the latest episode of the anime series, Sir Nighteye revealed that he believed there was an "energy" that was stemmed from the strong desire for a particular vision of the future. That everyone and their wishing energies converged together on Izuku Midoriya, and they believed so strongly in their positive vision of the future that it changed the actual future Nighteye had predicted.
It can be all too easy to write this off as the usual operatic type of shonen anime dialogue, but when combined with the knowledge of what comes later in the manga, perhaps this is actually something far more literal. What if these are literal energies that Deku was actually taking into himself thanks to the full explosion of One For All? What if this briefly tapped into his own hidden quirk?
The more we see of All For One and Shigaraki's mysterious doctor figure, the more it's looking likely that this doctor actually stole Izuku's original quirk from him for one of his many Nomu experiments. Considering he was the one to give Izuku the initial diagnosis, there's a chance he figured out Izuku had this kind of energy storing ability and stole it from him.
This would've been the end of that, usually, but thanks to Izuku inheriting One For All things have changed. One For All's base ability is stockpiling other quirks. The latest chapter revealed that these quirks weren't anything to really write home about, but have gotten stronger the further it has been passed on. Izuku's begun to unwillingly tap into these powers thanks to the increasing singularity of power, so what if he tapped into his own quirk in the Overhaul fight?
One For All has taken each of the vestiges' quirks and amplified them to a greater extent, and this must undoubtedly include Izuku. All Might didn't have a quirk of his own, but what if his being a Symbol of Peace so easily was a part of this too? Everything's been amplified, including Izuku's impact on those around him.
Having Eri's quirk go so wild not only allowed Izuku to reverse his One For All damage, but what if Eri actually restored his own quirk in the process? It's after this that Deku starts dealing with the One For All singularity, so if he has some sort of energy related quirk deep within him Eri's power could have helped to restore it to his body in some way. Izuku having an energy related quirk would explain why All For One looks so different with him too.
All Might's use of the power didn't have any of the electricity Izuku gives off, so why is Full Cowling so different looking from all of All Might's strength boosts all of a sudden? As we have learned from this series, every little detail of the world is important -- so why would Kohei Horikoshi make Izuku's power so drastically new without a reason behind it? Maybe it's because One For All is now a literal energy force that Izuku Midoriya is managing with his own hidden energy related quirk.
But what do you think? Could Izuku Midoriya have a secret energy quirk somehow activated by the collision of One For All and Eri's quirks at full power? Let us know your thoughts in the comments or talk to me directly about all things anime and other cool things @Valdezology on Twitter!