Ruthinea

A Prime Navigator who manages the pathways between stars. Likes anyone who can get the job done, doesn't like anyone else. 

"Older" sister of Mikaelas. Because of what her brother's like, she's had to grow up responsible. 

Their sibling who sometimes exists but mostly doesn't is Esthelia. There is a theoretical probability that Esthelia is older than either of them, but who knows really?