May I ask what happened to pearl Moon? Did he get corrupted?
I'm thinking, perhaps, a combo of corruption and damage (like Pink's original Pearl with her eye). These two woulda been "in service" during the Diamond's reign but would have eventually fallen into a group like the Off Colors because of Moon's damage and the two not wanting to be separated.
Post corruption/injury the two wouldn't have fused as often because Moon wouldn't want to taint Sun too. That would have been reserved for when the situation absolutely required it. And obviously from the ref sheet of Eclipse, they fused one too many times. : )









