Saw Venom and remembered my old Aberrant tabletop game with the assassin, Reflex (Mena) and the enemy assassin, Embrace, who ended up falling in love with one another. Embrace would disguise herself as Reflex’s trenchcoat and had to absorb/eat people to sustain herself. An affliction Reflex herself developed after a while.
Embrace was eventually ordered by her boss to take out Reflex and it turned out to be a sort of “absorb off” battle to see who could consume the other first. Reflex won and they sort of merged into one being with Reflex being the more dominate personality.
They eventually died in the last big standoff with Embraces boss.