I’ve mentioned before that I think Lapis Lazuli was intended as an explorer or scout for homeworld. I believe this for two reasons:

One: Lapis’s weapon, her water wings, allow her to travel through space at superluminal speeds, something that’s incredibly important for finding new planets to colonize, and only useful if you’re traveling to places that don’t yet have a galaxy warp or wailing stones



Two: The first thing she did upon being freed was draw the 8-pointed start of Blue Diamond, which is basically saying “I am Blue Diamond’s representative, don’t fuck with me”



Basically Lapis is Steven Universe’s version of the Silver Surfer: a being who searches the stars looking for planets for homeworld to colonize and consume. This is fucked up enough on it’s own, but then you remember this quote

Lapis Lazuli: Don’t you know anything, Steven? Your friends, they don’t really care about other Gems. All they care about is the Earth. But I never believed in this place…

and the fact that Lapis was here since the beginning

And you realize that at some point about 6000 years ago, Lapis Lazuli discovered earth and declared it uninhabited by intelligent life.

Lapis Lazuli is responsible for the entire plot of Steven Universe. She brought Homeworld to our doorstep, and that is why she was sealed in the mirror!