----
Aizawa considered himself as someone to lacked emotion.
Someone who didn't react much; like a black hole, devoid of any feeling. Granted, he felt some fear, like during horror movies that Hizashi, Midnight, and other colleagues subjected him to during movie night, but he was swift to hide it.
But now, as "problem child" (as he called him) demonstrated his quirk; Aizawa gets reminded on how infinite possibilities are with powers; and how terrifying they could actually be.
Aizawa becomes increasingly suspicious of Izuku after he develops a second quirk--and one that has nothing to do with his original strength augmentation. To prove his innocence, Izuku builds up the courage to tell his teacher something he should've from the start.
He tells Aizawa about the existence of One for All.