Soga has a cruel and violent personality, he likes to humiliate and attack people. This stems from the fact that he has been discriminated against due to his actions and his Quirk. He seems to think that everyone around him sees him as some sort of monster, and has developed a love of making other people suffer in place of him due to these circumstances.

He shows some signs of mental instability, as shown when he sees everyone around him with a mocking, condescending smile, and laughing at him, no matter who they are and what they are actually doing, suggesting he is unable to separate reality from his perception of the world. It is suggested that this perception of the world is what makes him so violent.

In spite of these flaws, he shows solidarity with his friends, who are other people who have been looked down on due to their Quirks. He shows a strong sense of loyalty and care towards them.