Solar was traumatized by Moon because he "killed Moon's brother" Meanwhile all he wanted was freedom from someone else's head and when separated Sun Moon's brother broke. Moon would do things like hit, tell and torture. Now Solar lives with a Moon and Sun from a different dimension where Moon isn't that much of a jerk to him though the trauma is not gone it's like a scar it will fade but never go away fully which is why when Moons mad he can be a bit jumpy now eclipse is back