I Won't Fail Again

During the final battle with All for one and Shigaraki, Izuku and the heros failed to stop him and Izuku watched as All his friends and classmates died before his eyes with him being unable to stop it because his body was too broken.

Before Shigaraki and All for one could kill him, Katsuki sacrificed himself like everyone else to save him from them.

He was taken away by Aizawa and Hawks and put in hiding along with Eri who began to see him as a older brother/father figure. Later Izuku broke down into tears over the fact he lost everyone and everything but he became more determined to get strong enough to stop All for one and Shigaraki.

After many years of training and multiple attempts along with loosing more and more friends and family along with countless millions of innocents because of All for ones Nomu army, he lost the will to live when he was forced to watch Eri get killed before his eyes and All for one steal her quirk.

Izuku broke that day and he went on a bloody path to kill All for one and Shigaraki, they all met in the destroyed ruins of Tokyo and fought the final battle where Izuku sacrificed himself to stop them.

After he closed his eyes and his breathing stopped he suddenly opened his eyes at the UA sports festival and in his younger self.