what does daemon mean when he says the black rats have gotten big

He’s most likely talking about the rat problem in the black cells / Red Keep , but in House of the Dragon it also works as a loaded insult —“rats” can mean spies, traitors, or people he considers beneath contempt. The line is usually read as both literal and political, with Daemon using it to sound ominous and contemptuous at the same time.

What it means

• Literal reading: the rats in the black cells have become unusually large, suggesting filth, neglect, and decay in King’s Landing.

• Symbolic reading: Daemon is also hinting at corruption, hidden enemies, or people quietly feeding off the court like rats.

• Fan interpretation: some viewers connect it to the show’s broader theme of the city rotting from the inside, especially after the rat-catcher storyline.

Why the line stands out

The phrase sounds like Daemon being poetic and threatening at once, which fits his character well. It’s the kind of line that can be taken as straightforward world-building, but also as a sharp bit of political shade.

In plain English

He basically means: “things in this place are getting nasty, and the rot is growing.”

TL;DR

Daemon is probably referring to literal rats , but the real point is the corruption and decay around him, with “rats” also doubling as an insult for enemies or traitors.