"Luckily, as he so often has before, the Ninth Doctor makes a friend that slowly resets his internal spirit level. It’s pointless to consider Nine without Rose, as she’s the young girl, also of humble origins, who teaches him how to regain his sense of proportion and his warmth. In return, she gets to meddle with time (she meets her dead dad, get him back together with her mum), and kill her own race of Daleks. Their relationship is symbiotic."