(The basic idea here is a friends to enemies to lovers type situation with a whole lot of angst / fluff in-between. For more intricate/specific details on plot, just ask. Rated MA for the possibility of extreme violence and other such materials.)
You find yourself on one side of a war with someone you could once call your friend standing on the opposite end from you. Your difference in beliefs has left the two of you estranged, seemingly in a state of permanence with no hope of reconciliation. Although the two of you may cross paths every now and again, your interactions are almost always fated to end in conflict with no clear winner ever declared by its conclusion. However, try as you might, no matter how deeply you may deny it, something within your soul stops you from killing her at every given opportunity.
And it's driving you crazy.