Tenya Iida

Tenya seems stern and even intimidating at first glance. He is a simple, intelligent, disciplined person. Due to his generally quite hyperactive and intense behavior, he often has particular tics, such as moving his arms in a specific way or suddenly contracting his body. However, he rarely deviates from his usual severe expression. Tenya has a tendency to take everything very seriously and often jumps at conclusions.

He is fully dedicated to his studies and loves learning new things. As a delegate of his class, he is also obsessed with organization and discipline, expecting his classmates to be as rigorous as he is. He also considers himself personally responsible for their safety and considers it his duty to protect them from dangerous situations. He also knows how to react quickly when something unexpected happens.

He holds a great deal of love and respect for his older brother, striving to be a hero just like him. Because of this, his character takes a darker turn when Ingenium is attacked and crippled by the Hero Killer: Stain. During this time period, his mind focuses only on getting revenge and eliminating Stain for his crimes, unable to think of anything else. After the Hero Killer confronts him with this truth and after some words of inspiration from Izuku and Shoto, Tenya eventually sees why he was wrong and subsequently abandons his desire for vengeance. While he still hates Stain for what he did to his older brother, Tenya is nevertheless takes his words to heart and vows to become worthy of the title hero.

Tenya is also very committed to following the rules and sticking to protocol. When Katsuki was kidnapped by villains, Tenya firmly stated that they couldn't go after their friend because they weren't allowed to use their quirks for hero work, though he eventually relents and goes with his friends to ensure they don't engage in physical combat with the villains when going to rescue Katsuki. However, as time passes, he eventually learns how to become more relaxed and less stiff with the rules.

This is most notable during the Paranormal Liberation War, when Tenya decides to go join Izuku and Shoto, who're fighting Tomura Shigaraki, despite the fact that doing this would be violating orders, because he suspected they were in trouble and wanted to help them.