Character A who’s rough, tough, hardly ever shows they’re in pain from things most people struggle to come back from, does everything themselves and doesn’t lean on anyone + Character B who has a much softer personality, worries over them, tries to have their back when A hardly lets anyone caretake them, but knows they’re capable.
Then A going through something so bad or getting so injured that they just become a whimpering mess in B’s arms and actually lets B take care of them, worrying B even more. Then B goes full “who did this to you,” scorched earth mode to protect them/get justice.