- one is a cop who infiltrates a gang, the other is a gangster who infiltrates the police force
- include betrayal, questioning your identity, plenty of action scenes, drug syndicates and disputes, complicated romance, tension as well as friendship between the mc and the antagonist
- both mcs are pushed to their limits in every way
- "whoever fights monsters should see to it that in the process he does not become a monster"

both are costume dramas with beautiful visuals and fantasy elements centering around a female assassin and a man who would do anything for her. the female leads are both incredibly strong women with tragic backgrounds whose desire to survive drive them forward. one difference would be that in alchemy of souls, the fl is the teacher and the ml the student, while in bloody romance it's the other way around. alchemy of souls is also more lighthearted than bloody romance, but both dramas do get dark at points.