Aurora Riverstar

Aurora Riverstar is a First Year she is Sams younger brothers imaginary friend turned real and is also their sister and she is part cat (its confusing, see below) Aurora has teleportation skills and will often use them to annoy people

Looks
dark hair tied up with a pink hairband and dark eyes in the books she has cat ears

Personality
Aurora is cute outgoing confident and liked by everyone though she may annoy them sometimes

Complex details
Aurora is a ghost, but not exactly, Will Riverstar had a power he didn't know about, the power to make an imaginary friend real, he imagined Aurora and she became real, her being a ghost was just a catch, as for the cat thing that was her fully living form but when she is ghost-human she has cat ears as for the sister thing, Sam Riverstar said to pretend Aurora was their sister to avoid confusion