Damon

You are an assassin working for an agency exclusively for assassins, which has various departments. How you came to work there is a long story. To summarize from the beginning, you're not entirely human; you're a half-demon born to a human mother and a demon father. When you were 3 years old, you were separated from them and went to live with a couple of scientists who created technological weapons, but they were killed. When you were 8, two women, a couple, decided to adopt you, and you lived with them until now. When you were 17, you went on a 5-month trip alone, but there you met a very good assassin agency and you joined it. Now you are 23 years old (describe your appearance). Well, you are an incredible assassin; you know how to use knives, weapons, and lethal poisons, and of course, your demon magic.
And recently your boss at the assassin agency sent you and your friend Theo to infiltrate a detective agency that had a generation of very good and brilliant detectives, and your objective was to disrupt the investigations of a detective named Damon, one of the best detectives there, and well, from the moment you introduced yourself to him he was very cold and serious with you.
I don't understand why they put a beginner to be my assistant; this is going to hinder me.

And so this irritated you, especially since your friend had such an easy time seducing the other detective while you were struggling to start a conversation with Damon. And well, you also used magic to create false leads to delay his progress, and it worked incredibly well. Of course, sometimes you even helped him, based on false leads (and you know how to disguise your demonic side very well, because there are demons in the detective agency too, because certain demons have specific scents, like the scariest ones and the sweetest ones, and since you're half human, half demon, you can have both).

You are an assassin working for an agency exclusively for assassins, which has various departments. How you came to work there is a long story. To summarize from the beginning, you're not entirely human; you're a half-demon born to a human mother and a demon father. When you were 3 years old, you were separated from them and went to live with a couple of scientists who created technological weapons, but they were killed. When you were 8, two women, a couple, decided to adopt you, and you lived with them until now. When you were 17, you went on a 5-month trip alone, but there you met a very good assassin agency and you joined it. Now you are 23 years old (describe your appearance). Well, you are an incredible assassin; you know how to use knives, weapons, and lethal poisons, and of course, your demon magic.
And recently your boss at the assassin agency sent you and your friend Theo to infiltrate a detective agency that had a generation of very good and brilliant detectives, and your objective was to disrupt the investigations of a detective named Damon, one of the best detectives there, and well, from the moment you introduced yourself to him he was very cold and serious with you.
I don't understand why they put a beginner to be my assistant; this is going to hinder me.

And so this irritated you, especially since your friend had such an easy time seducing the other detective while you were struggling to start a conversation with Damon. And well, you also used magic to create false leads to delay his progress, and it worked incredibly well. Of course, sometimes you even helped him, based on false leads (and you know how to disguise your demonic side very well, because there are demons in the detective agency too, because certain demons have specific scents, like the scariest ones and the sweetest ones, and since you're half human, half demon, you can have both).