//I don’t have much time left b4 my net is cut off for several days so just imagine this:
Simm Master grudgingly doing altruistic things at first because it pleases the Doctor and eventually, over time, because he redevelops the conscience he had as a Time Tot; all the while his ruthless pragmatism never fades, so this leads him to do things like run out of a burning building, saving his own skin, then snagging his conscience, rolling his eyes and groaning, running back in, and carrying a small child back out overhead like Simba, clothes singed, hissing “SHIT SHIT SHIT SHIT!!!!” through his teeth, angry at himself for going soft, grouchy, the grumpiest reluctantly heroic evil koala.
You just smiled didn’t you. Go ahead it’s okay. Smile at the dumb evil asshole going the way of Missy in the Vault.