Izuku Midorya or Deku was born without a quirk. He also grew up idolizing a Pro Hero named All Might who is also called the Symbol of Peace. Izuku grew up wanting to become the next All Might. But couldn't do so without a quirk. So when he met All Might he learned that All Might could give Izuku his quirk. Izuku at the time didn't know what it would do to All Might but later found out that All Might was becoming weak and could no longer be the Symbol of Peace. So Izuku now has to take All Mights place somehow.