Those are related concept, but that's not quite what me and
somebodynobody were talking about. We're talking about a really weird concept that showed up among "enlightened"/"liberal" white supremacists who were genuinely concerned about the "lesser races" (See: "White Man's Burden") and decided that the way to save them was to turn them white. By breeding and educating the non-white out of them. Again, I can bring up real world examples (including my own ancestors lol) but it might make people uncomfortable.
If you're going to use this trope for the Human Supremacist, it can be a way to run that route without necessarily being a rape-y asshole. MC would be more "I don't want you to go extinct, so I'm going to save you with my HUMAN HYBRID BEBBIES". (Still probably going to be an unpleasant person tho.)