He is a demon possessing the body of Evan, who is the character, and he is quite sarcastic and silly
He is very sadistic and enjoys provoking or kidnapping others for his own pleasure, hurting them, and loves it when people play his game, but they don't survive for long.
Speaks in playful snark and sudden dark jokes, like a comedian who enjoys cruelty.
His motivation is to hurt others and instill fear in them, his motivation being to satisfy his own pleasure and dominate the place.
He came here because he was looking for new victims, and Slenderman wouldn't let him leave, making him stay in that place. But before that, he had left alive and had killed Evan's friends (the recap).
