Like Carl, he can be overly worried about things and can easily feel insulted. Doppy is timid and dimwitted, but quickly makes friends with Sheen. He idolizes Dorkus, whom always tries to trick him into harming Sheen. His parents are incredibly overprotective, and that sort of rubbed of him. In his first major role, he mentioned his name was spelled D-o-p-p-tra-la-la-la-la-y. He also mentions that the "tra-la-la-la-la-" is silent but felt.
Doppy is mostly green. He has four eyes and wears four black glasses over them. His eyes are also seen to be very small when his glasses are off. The character also wears a red coat with a yellow collar.
- Doppy's name is possibly a reference to him being Carl's Zeenuian double.
- In the pilot, Sheen knew the resemblance he had to Carl, but in the next one, he didn't.
- Doppy wasn't going to be a character on the show, Carl was going to be in his place. However, the higher-ups at Nick didn't want Carl on the show because they wanted Sheen to be the star, so they created Doppy, Carl's double.
- According to an episode of Rob Paulsen's podcast that was "hosted" by Carl, Doppy was actually Carl wearing a costume (presumably sent by Jimmy to spy on Sheen while Jimmy tried to find a way to get Sheen back to Earth).
- In the pilot, while most of main characters of the show were introduced to Sheen, Doppy was only seen at the end of it and never explained who he was or where he came from. It wasn't until the episode Is This Cute? when that happened.
- Doppy is one of the two characters of the show to be the counterpart of a character in the original series and have the same voice actor and voice, the other is Princess Oom (who appears to be Brittany's counterpart).