Shoto originally had a cold, aloof personality, which stemmed from his abusive upbringing and complicated family life. Focused and unemotional, Shoto preferred to keep to himself instead of hanging out with other people. After future events, however, Shoto notably became more sociable and kind, even gaining a sense of humor and occasionally smiling, although still retaining some fragments of his previous distant attitude. After a while, he begins opening up more to his classmates and has lightened up from his usually serious demeanor. Nonetheless, Shoto is not quite used to socializing yet, coming off as a bit dense when it comes to understanding certain phrases and figures of speech.

While usually quiet and reserved, Shoto did initially possess a moderate level of arrogance, which, combined with his solitary tendencies, sometimes made him take the initiative without considering the opinions of others, displaying confidence that he could take on any obstacles with his own strength. He used to be much more unfriendly as well. Even in the present, Shoto seems to prefer acting alone, although only for practical purposes since doing so allows him to unleash his full power without having to worry about friendly fire. Calm and composed, yet brutal in combat, Shoto is well-grounded on the ethics of heroism, only wishing to subdue his frozen opponents as opposed to killing them by prolonging the freezing. 

Shoto had a deep loathing for his fire abilities, which he inherited from Endeavor, as it symbolized his father's wickedness towards him and his mother as well as what he was born to be. As such, Shoto decided to rely solely on his freezing power and never use the other half of his Quirk in battles (save only for melting his ice), going so far as to cover his left torso and arm with ice in his first Hero Costume to symbolize his rebellion against his father. Shoto often felt bothered by Endeavor's mere presence, and could barely contain his anger while talking to him, especially whenever the Pro Hero brought up the purpose he had intended for his son since before birth. Ironically though, Shoto's animosity towards his father made him more like how Endeavor was, being apathetic and indifferent towards others while obsessively focusing on his own goal of rejecting his father.

 Despite being scarred by her when he was a young child, Shoto shows no hate or disliking towards his mother, visiting her often. Despite his difficult past, Shoto doesn't allow his hatred of Endeavor to completely cloud his judgement and still acknowledges him for his skills and capabilities as one of Japan's top Heroes.

If you could sound similar to his English VA, David Matranga, that would be great, but it is not required!

English VA Example: https://youtu.be/HT1QlilYz7A