I did like the backstory, but I'm a bit confused what the "secret" is supposed to be. Sounds to me like All Might will die soon because Deku has his power now (Deku gets stronger and therefore All Might gets weaker), but wasn't that obvious from the start? To be honest I was expecting All Might to die at the end of season 1, but I guess we'll get that sad moment later.
Well, maybe there is more to it than we know so far.
Shout by SqueakyNarwhalBlockedParentSpoilers2017-08-19T17:08:29Z— updated 2017-08-26T02:03:54Z
Man, that backstory for One For All/All For One was amazing! It's really interesting to see the history of quirks first appearing and how it caused a lot of unrest among society. Reminded me a lot of the themes brought up in X-Men comics, which is fitting considering that MHA takes a lot of inspiration from western superhero comics.
Also, if All Might could just stop giving off so many death flags and let me not get emotional for an episode, that would be great.