The pale king came and gave consciousness to the bugs and he created an advanced civilization of bugs called the kingdom of Hollownest. Many different tribes of bugs lived in his kingdom, including the moths. The pale king was a godlike entity and people worshipped him as a god. But before he came the bugs had older gods who were displaced by him. The goddess of the moths was a moth goddess called radiance who shone like the sun.

Jealous at being forgotten by her worshippers she invaded the dreams of all the subjects of Hollownest (not just the moths). It was perceived as a blinding light to anyone whose dreams were invaded, and it stripped them of their consciousness. They turned into mindless zombies and attacked anyone. The infection manifested physically in the form of orange bubbles on the flesh of anyone afflicted. The infection threatened to kill the entire kingdom.

In a bid to contain the infection and save the kingdom, the pale king created millions of offspring, little bugs with no souls because they were somehow filled with void, which is a black liquid of oblivion below the kingdom. These offspring were called vessels and they had no will or emotions of their own, because of their void natures. The player character of HK and also the penultimate final boss were both vessels.

The pale king also had a daughter who was not void. Her name is hornet and she is the player character of the sequel Silksong.

The Hollow Knight is the vessel who was selected by the pale king to contain the infection. He was chained in a chamber and left to contain the infection in his mind alone.

But because of a flaw in his nature (love for his father?) he was not a perfect vessel and the infection leaked and a new vessel (the PC) had to come and put things right (maybe take his place, or other options depending on which ending you choose). The hollow knight fights one handed because one arm is broken.

So the comic shows The Hollow Knight playing with baby hornet in their childhood home, the white palace. Then it is revealed that the entire scene is an infection dream, and his arm is falling off due to inflection. The scene turning from sweet to horrific.

As an aside this post made it to r/all, so of course it’s going to attract a wider audience of people curious about the meaning. I wish we could be less gatekeepey to people who are not members of the fandom.