'House of the Dragon': Who exactly is the Crabfeeder?

In the Game of Thrones universe there are plenty of morally grey characters.

The original show had the often dubious likes of Jaime Lannister and Theon Greyjoy, while House of the Dragon has already introduced the sneaky Daemon Targaryen, and the (arguably even sneakier) Otto Hightower.

But some characters are just...