It's generally not a good idea to talk about the age of the Antichrist.
Exz, you described exactly the devil, as it has become fashionable to portray him in American movies, in a suit. He is always there, right in front of a person, when that person turns away.
In my opinion, if the Antichrist existed, he would look like... a boy. Quiet, keeping to himself. Gloomy. If he walks past people, they feel uneasy, for example, they stop talking, maybe even without realizing why. Restless... or, on the contrary, "devilishly" calm. His gaze wanders... his mind is immersed in thoughts known only to him... if someone wants to argue with him, for example, they immediately fall silent, not even having time to open their mouth. The boy only needs to direct his empty gaze at the unfortunate person. If, for example, someone is running, and runs into him, they immediately recoil in horror, feeling his devilish aura, without realizing it. If he walks down the street, and a pedestrian is hit by a car, everyone runs around, screams, panics, calls emergency services... and he simply walks through the dense crowd like a knife through butter, it unconsciously parts before him, looks at the corpse with a sad, gloomy look, and then leaves... or says something devilish. Like, "one more soul in the kingdom of evil," and so on. :)
That's it.