Board Thread:Site Discussion/@comment-30940727-20170806154038/@comment-33871937-20171205114115

If we take the anime and manga at face value then [One for All] is actually fairly simple by my estimates. It's also important to factor in the author's intentions and the tone of the story. BNHA is what could be considered a pure, straightforward shounen story done incredibly well. In its current incarnation, there seems to be no intention of suddenly deconstructing or flipping the premise on its head. It isn't purely lighthearted, but it's not going to suddenly cut somebody's head off or kill off half the cast. Like I said, fairly straightforward.

[One for All] stocks power from its previous wielders, and allows the current user to tap into that power. I don't think the growth between users is exponential - it's linear. The reason All Might is so ridiculously strong, more so than the strength of nine men should reasonably be? Plot, and artistic license is one incredibly valid explanation, but the other ties in with what a previous comment claimed. The original quirk was probably not a [Strength Stockpiling] or [Strength Enhancing] quirk, but rather a [Strength Maximization] quirk. The original may have unlocked 100% of the user's physical capacity, allowing them to perform feats such as lifting cars and the like, which is possible in real life with enough adrenaline. [One for All] and the [Strength Maximization] quirk mutated together, creating the current incarnation of [One for All].

When transferred, *100%* of the previous user's strength is transferred to the new wielder, and added to their own, maximized strength. That's only the second wielder, and you've already got twice the strength required to break through bricks and lift cars. Third transfer happens, and takes 100% of the second wielder's maximized strength, which includes that of the first. And so on, so forth. If we take the spirit of BNHA, and the author's intent at face value, it is simple enough to explain. Punching up a rainstorm is just artistic license, hearkening back to the days where superman's powers depended entirely on the whims of whatever author was penning his comic at the time.

NOW, correct me if I'm wrong, but originally Horikoshi had intended for the show to be a fair bit darker. He's stated in more than a few interviews that he had always wanted to move past the innocent academia setting, and transition into more mature, adult themes. Drugs, sex, and fame, etc. A loss of the innocent charm the series has right now. If you take that into account, there's plenty of alternative, scarier ways of thinking about [One for All]. Consider this one fact, which cannon has yet to answer. If the original wielder of [One for All] DID have an 'invisible quirk' that granted no benefit save that it could be passed on, one so hard to identify that even his own brother was unaware of it... Then how on earth did the original owner know that he could pass it on in the first place?

That in itself calls a number of things into question about what we know. Why did All for One give his brother a quirk anyways? Did he just want to break his mind? Was he hoping to help him, or control him? Is there a lot more to this story than we've been told so far? Maybe, just maybe, everything we've been told about All for One and [One for All] is completely wrong. Consider as well, that out of nine different bearers, there had to have been at least one who already possessed a quirk beforehand. If that's the case, then why hasn't [One for All] mutated further from contact with these abilities? There's also the vision Izuku experienced at the Sports festival - it can't be anything supernatural like the 'spirits of previous wielders' since All Might was one of the figures, despite still being alive. Wild mass guessing begin.

INSANE THEORY: What if [One for All] is not actually a 'quirk that can be passed on to others'? What if [One for All] is actually a sinister parasite of some sort? A form of immortality for All for One's brother to bide his time and attempt a full revival somehow. Maybe the heroic brother wasn't so heroic after all? But then again, this edges on fanfiction territory. Just keep in mind that the author COULD have had something like this in mind, but was forced to scrap it since it didn't fit the series' final setup. Or maybe it's still coming, and we just haven't realized it yet.