so there has been a lot of justified discussion about thirteen’s confusing characteristics when it comes to her morals. for example:

in the woman who fell to earth, the doctor reversed the dna bombs on tzim sha which pretty much guaranteed his death, then got angry and shouted “you didn’t have to do that!” when karl pushed him off the crane even though he was dying anyways

in arachnids in the u.k. jack robertson kills the giant spider in the ballroom, calling it a “mercy kill” since the spider was already slowly dying from suffocation. it’s true, it did save the spider a slow painful death, but the doctor still gets absolutely enraged

towards the end of the witchfinders king james kills morax becca savage, abolishing a real threat, but the doctor still scolds him and gives him the silent treatment for a while

a lot of people are calling this either poor writing or poor execution, but here’s the deal: it isn’t. the doctor loathes unnecessary acts of violence that are performed out of rage and nothing more. robertson didn’t shoot the spider with the intention of it being a mercy kill, he shot it out of anger and self preservation even though it was no threat to him. king james killed the morax becca savage out of adrenaline and his desire to cleanse the world of evil as according to “god’s will” aka murder, aka bullshit. karl didn’t HAVE to push tzim sha off the crane, he just wanted to be a hero

the doctor doesn’t do unnecessary violence, and this is just a more introspective and creative way of showing that. it’s not a conflict of her morals, it’s her morals being VERY important to her. don’t forget that