Either you or crush/family figure is a villain. You're fighting one another and the villain wins, then takes them to their base, where they start taking care of the hero. It turns out the villain found out about the hero's identity and learned something that made them worry for their little opponent (could be age, an injury, a physical/mental illness, something about their backstory, something bad they go through, they're being abused as a civilian, they're refusing to take care of themself, etc) and now they just want to look after them and keep them safe. Over time, the hero starts to accept and enjoy it
