Follow Your Passion: A Seamless Tumblr Journey
My headcanon! Back in old days, most adventurous Hallownest inhabitants used to hunt albino Alubas for Pale King's palace. Anyway, path = pilgrim's way
You don't get it the more I think about it the more these two are literally the same goddamn character in different circumstances and I'm about to list the reasons I know this.
Ok let's get the obvious out of the way. Both the Pale King and The Radiance are described as "a light" by the seer, which already implies a connection. (Terms like The Old Light for Radiance and Beacon for Pale King allude to this as well) This could be a physical thing, but it also alludes to the type of power these two hold: both of them are capable of affecting bugs' consciousness.
The Pale King gave them sentience and The Radiance made the Infection. It's unknown whether the Moth Tribe had sentience before the Pale King but considering they were able to harness Essence for themselves it seems likely. Either way the Radiance probably gave them some kind of consciousness before the Pale King showed up.
Ok so PK may have been the one to say the famous line but it 100% applies to The Radiance as well. Her one motivation is to be remembered, presumably out of self-preservation. To accomplish this she entered bugs' dreams and placed them under a hivemind. Not something we'd call ethical, but hey, neither is killing thousands of your own children to find one with no mind and seal it in a temple.
If we interpret Pale King's intentions as wanting to preserve his kingdom as opposed to keeping more bugs from being infected then he also falls into a similar mentality.
Hollow Knight's biggest theme in general is "all things must come to an end eventually", and The Radiance and the Pale King both cause suffering trying to counter that. One wanting to preserve her memory, the other his kingdom.
The fuckin horn thingies
Both of these headpieces look like crowns for obvious reasons, but The Radiance's "crown" is a lot smaller, alluding to her status as a fallen deity. (This doesn't mean anything in-universe since thanks to the statue in Crystal Peaks we know she always looked like this, but it's an interesting design choice)
If you wanna look deeper the colors between their eyes and face are inverted
PK gives bugs a mind. Radiance takes it away. They have the same goal and the same power but do the exact opposite. So while PK has a lighter face and darker eyes Radi has a darker face and lighter eyes. This is something they share with the bugs whose minds they've altered; conscious bugs have dark eyes while infected bugs have orange pupils.
I know these details were probably not that deep upon conception but on the off chance they were I wanted to bring them up because they cool.
Anyway in conclusion we have
Similar mind powers
Similar symbolism
Similar desires
Similar "ends justify the means" mentality
We don't get much in the way of actual characterization since we only get like 4 lines out of each of them but their motives and actions seem too similar to not notice.