Funny thing, hindsight. With The Ripple Effect, Malorie Blackman managed to expand on an almost blink & you'll miss it discussion in Remembrance Of The Daleks, with the Doctor himself proving the rule debated in that café......
DOCTOR: Ah. A decision. Would it make any difference?Finding himself & Ace stuck in a temporal plexus- a sort of cosmic quicksand- the man who'd made such a decisive intervention in the Dalek civil war is forced to face the consequences of his own snap choice to force a star to go supernova in a bid to escape said plexus.
JOHN: It would make your tea sweet.
DOCTOR: Yes, but beyond the confines of my tastebuds, would it make any difference?
JOHN: Not really.
DOCTOR: What if I could control people's tastebuds? What if I decided that no one would take sugar? That'd make a difference to those who sell the sugar and those that cut the cane.
JOHN: My father, he was a cane cutter.
DOCTOR: Exactly. Now, if no one had used sugar, your father wouldn't have been a cane cutter.
JOHN: If this sugar thing had never started, my great-grandfather wouldn't have been kidnapped, chained up, and sold in Kingston in the first place. I'd be an African.
DOCTOR: See? Every great decision creates ripples, like a huge boulder dropped in a lake. The ripples merge, rebound off the banks in unforeseeable ways. The heavier the decision, the larger the waves, the more uncertain the consequences.
As you might imagine there's a rather big explosion! So forceful a whole other reality is created. One in which the previously feared former Kaleds have become respected teachers, with Skaro as a universal centre of learning. Lovely stuff, you might think. As does the girl with the Nitro-9, willing to give this new state of universal affairs a chance. But the man she fondly dubs Professor has a bee in his bonnet, seemingly unwilling or unable to accept the fact that his oldest enemies have changed. With good reason, perhaps. They have of course attempted similar gambits at least twice before- following his first regeneration.......
DALEK: I am your servant.And again shortly after his tenth such change, writer Mark Gatiss referring back to Power in a New Paradigm Dalek's attempt to pass itself off as a good old fashioned soldier-boy.
LESTERSON: It, it spoke! Janley, did you hear it? It can actually talk.
DOCTOR: It can do many things, Lesterson. But the thing it does most efficiently is exterminate human beings. It destroys them, without mercy, without conscience. It destroys them. Utterly. Completely. It destroys them.
DALEK: I am your servant. I am your servant. I am your servant. I am your servant. I am your servant....
DOCTOR: What are you doing here?More than just fezzes in common for the Seventh & Eleventh Doctors, then, as they joined their former selves in vehement opposition to the hideously mutated children of Davros. But is the line between he & they so black & white? Consider what the undoubtedly traumatic experience of believing himself to be the sole survivor of the Time War did for the Ninth, the first incarnation to seemingly be willing to follow their train of thought & threaten to use it against them.
DALEK: I am your soldier.
DALEK: I am your soldier.
DOCTOR: Stop this. Stop now. Now, you know who I am. You always know.
DALEK: I am alone in the universe.But then why should he "Have pity!". For as he also notes, "Why should I? You never did." These things clearly die hard, going by his latest self's encounters in Into The Dalek & The Magician's Apprentice.
DALEK: So are you. We are the same.
DOCTOR: We're not the same! I'm not... No, wait. Maybe we are. You're right. Yeah, okay. You've got a point. 'Cause I know what to do. I know what should happen. I know what you deserve. Exterminate.
We might conclude that this is not a recent development, though, as he set out his stall during his first meeting with them!
DALEK: We wish to escape captivity. Go out and rebuild the planet Skaro. Our oxygen distributors will be subjected to waste radiation by the ejector capsule.Has his quest to stop them really given him the right to claim the moral high ground, though? As that meeting of minds in Van Statten's Utah vault shows us, possibly not. That he could not bring himself to stoop to their level even in many of his darkest hours is surely some measure of his depth of character?
DOCTOR: Nothing can live outside if you do that. Nothing.
DALEK: Except the Daleks.
DOCTOR: When do you intend to put this into operation?
DOCTOR: This senseless, evil killing.
Something buried deep in his make-up just won't let him rest while they attempt to bring the universe around to their way of thinking, though! As he once told Ace, Dalek hunting is a terminal pastime, which nevertheless has never stopped him trying. And it's unlikely we'll see their final end, to quote the Second Doctor, any time soon.
Simply because, as observed in Daleks In Manhattan "they always survive, while I lose everything." Fuel to the fire, then. A fire which has raged across time & space for aeons.
"You are my enemy! And I am yours. You are everything I despise. The worst thing in all creation. I've defeated you time and time again. I've defeated you. I sent you back into the Void. I saved the whole of reality from you. I am the Doctor. And you are the Daleks."And as he'd observed to his companions in The Edge Of Destruction "As we learn about each other, so we learn about ourselves." Fitting then that the Daleks taught the Doctor the sort of thing he should be standing against, even if the lines of opposition are often blurred!