Shadow is a brooding loner, to put it bluntly. He usually acts with a cool and businesslike indifference, only occasionally showing his vulnerable side. He is rarely seen with others for an extended period of time and usually distances himself from essentially everyone. He is usually soft-spoken, silent and doesn't speak much, but he always knows exactly what to say in combat. However, Shadow never bluffs. If he makes a threat, he has every intention of carrying it out.

Shadow also does not mind boasting about how powerful he is, calling himself the "Ultimate Lifeform" and like Sonic can be extremely arrogant, often belittling his opponents and insulting their lack of strength. He believes no one can beat him, and tends to see anyone as a fool for challenging him. Shadow also has a ruthless and merciless edge in combat that all other characters in the series lack, and displays a natural "killer instinct".

Shadow's infamous ruthlessness and aggression leads to fear and a nervousness that inhibits characters from his unshakable intent or sheer power in combat. Numerous characters from the Sonic series have shown absolute dread from encountering Shadow. Shadow's enemies never treat him lightly; he is one of the very few people Sonic takes seriously and acts hostile towards.

Alongside his dark and violent demeanor, Shadow can be smug and stubborn. He treats others in a very callous manner, throwing in his opinion no matter how cold-hearted it is and not caring for whatever the response is. Shadow is also shown to have a sharp wit.

You can base this interpretation on his past voices. If not, well... Alright. Shadow. Shadow should sound... Like a 9.7 on the edge scale. But not ridiculous edge. The kind people actually take seriously.