Royal Erebus (the oldest and genderfluid child of Luna and Pharynx), takes their job of leading creatures to the afterlife very seriously. They know that many deceased, and their families, depend on Erebus to take care of loved ones in a delicate manner. It takes a toll on the oldest royal, but they find their work immensely gratifying. They struggle to connect with other ponies their age, especially since the first thing that comes to mind is "hey, I just helped your relative move on from the mortal coil". Erebus struggles with acute social anxiety and does better with one pony at a time, which is easy with work and hard with the rest of life. They are very close to their younger brother, mother, and "extended family" of Twilight and her children.
Prince Cassiopeia (commonly known as Cass) takes great pride in his work, which he says is the most fun job in the world. As heir to Luna's throne and creator of constellations, Cass looks forward to making those in Equestria happy and in awe of the night sky. With his older sibling in such a time-consuming role, Cass took it upon himself to volunteer to follow in his mother's footsteps as next in line for major royalty. He looks a lot less like his father than Erebus, but has one of the largest changeling appetites Pharynx has ever seen. Cass, in an attempt for extra love being thrown his way, primps and preens in a way that would make even the proudest pegasi turn their head. Unlike his more "bug-like" sibling, Cass is covered in soft, downy feathers and is a magnet for cuddles and snuggling (which he happily allows). Cass has many friends, but is especially connected to his cousins Solaris and Blueberry Tonic.