Interesting fact about the Constant Moon.

[Waoling]

he came to learn what the moon above had always known: Wormwood the Lonesome does not belong here.

Why wouldn't the moon belong here? Unless the Constant use to only ever have the Sun, and the moon came later but before the shadow. 

[Gi-Go]

Is English not your native language? Read the line 5 more times. 

[Bumber64]

17 hours ago, Gi-Go said:

Is English not your native language? Read the line 5 more times. 

Pretty sure Waoling is Chinese. Regardless, the line is vague enough to imply that neither the moon nor Wormwood belong.

Usually Earth's moon is considered "alone" because it's separate from the Earth. (Having split from it, in fact. However, the cultural concept existed before we figured that out.)

I'm pretty sure "the Constant" includes the normal game world, the moon (Alter), the Forge, and the Gorge. Since the quote doesn't specify where "here" is, it could just be referring to the normal game world, where lunar entities are at constant war with shadow entities. In this case, we know nothing about the creation of the Constant's moon. Just that the surface and caves of the world are ruled by shadows who really don't like lunar entities.

We might theorize that Alter used to exist on the surface in the past, but was banished space after losing to the shadows. This would be a parallel to the creation of Earth's moon. I don't think we've been given any evidence of this, but it's interesting from a storytelling perspective.