Ooooh yes, I can see that - that Aleks might want to use her/their power to make a world for Grisha only, or raise Grisha up above everyone else, while Alina would be more focused on helping everyone, even people who were not at all grateful for her aid. And to your point about her being feared and hated - god, now I'm imagining scenarios in which she's threatened and he goes feral a la Kaz & Inej. This is some good AU.