The Antagonist is a being made of shadows, so he usually appears as a pitch-black humanoid, with what appears to be horns on the sides of his head. He has a scar across his right eye, so it's usually shut, and his mouth isn't visible unless he's eating something. His eyes are white and void-like, though sometimes he can be seen with them pitch black with small white pupils. He dons a pale red cape and a maroon sweatshirt, along with similarly maroon boots and dark brown fingerless gloves.
The Antagonist (or, preferably, Antag) is a character that existed in J-1, but when J-2 was created, Antag was wiped from that universe. So, Antag decided to try to go to that universe instead of staying in J-1, which he was able to, due to the ability to travel the Juiceverse at will.
Unfortunately, he couldn't yet, as Phantom - a ghost that was bound to him with unknown methods or reasons - didn't want to go. Antag tried to go on his own, but he was weak when he arrived in J-2, he just barely managed to go back to J-1 without losing consciousness. Long story short, Phantom had to follow Antag wherever he went, otherwise Antag would grow quickly weak and slip into a coma, dying soon after.
Due to this, Phantom got to get away with following Antag to J-2, and to each different universe that Antag went to. Antag was even blackmailed by Phantom once, being forced to allow Phantom to bring a cloning machine from J-10 to J-11. Now he runs a hidden shop in Ruby City, challenging players and rewarding them with valueless currency to spend on items and cards.