I think that they all represent different houses, which I will explain.

Darkstalker: Slytherin; he's cunning, ambitious, and most of all, he will do WHATEVER it takes to accomplish his goals                                                                                                                                                             -------------------------------------------------------------------------------------------------------------------------------

Clearsight: Ravenclaw; she's incredibly intelligent,  witty, and remarkably wise                                     -------------------------------------------------------------------------------------------------------------------------------

Fathom: Hufflepuff; he's caring and he tries to see the good in even the most broken\evilest of minds. I think that he would also benefit from the influence of the others in Hufflepuff.                      --------------------------------------------------------------------------------------------------------------------------------

Indigo: Gryffindor; she's super brave, bold, and she will not let anyone boss her around.