I guess we have to pay lip service to Compassion being the female companion, Fitz Kreiner being the male companion, and the Pilot being the Eighth Doctor.
It seems that a precedent has been established at the induction of FP that linkage by association is allowed in presence of additional common characteristics (again, not indiscriminately). For instance, timeships are TARDISes because Great Houses are Time Lords and timeships are their time ships.
Thus, if we agree now on the Ship being the Doctor's TARDIS, then its Pilot must be the Doctor and the male and female companions must be companions of the Doctor. At this point, we face a multiple choice question. Since I only know Fitz from one audio and you've all seen I'm not familiar with Compassion, I cannot judge how telling their descriptions in Toy Story are. I defer to experts.