2. Viciousness
Although the Doctor tries his damned hardest to be a good man, there are times where even he gets a twinge of anger running through his veins and he does things that might be more akin to a certain renegade Time Lord rather than the show's titular one. The Ninth Doctor, for example, seemed to always be in a grumpy mood (in his defence, he
had just destroyed his entire planet) and the Tenth Doctor was a "one chance" sort of guy. The Eleventh Doctor, meanwhile, also has had his moments but none of the aforementioned have caused his companion to psychically
leave like the Fifth Doctor did. In Resurrection of the Daleks, the Fifth Doctor had the chance to straight up kill Davros, the infamous leader of the Daleks, which would have saved him years (centuries?) of heartache and loss. Tegan, one of his companions, begged him not to go through with it but when he eventually decided against it, the damage had been done. Tegan revealed that she could no longer travel with a man who was harbouring so much anger that he could kill another in seemingly cold blood. This time, even the Doctor had crossed the line.
