Prat is the second developer of Melvor Idle. He comes up with ideas of weapon and new concepts, both Prat and Malcs (aka MrFrux) balance and “number crunch” it, and Malcs codes it into a new update.
Some things in the game named after him are Cape of Prat and Prat, the Protector of Secrets.
His profile picture in Discord may mean that he likes penguins. His role in the server is “Level 98 (Some Random)”. When asked what his profile picture was, he once replied “It’s a person riding a penguin into penguinland to more penguins...”
It also says that it was Prat's idea that you had to have 100 various dungeon clears to be able to use Ancient Magiks.
Maybe we shall know more about him as time goes on.