How to Be a Dark Hero’s Daughter

I became an extra in a detective novel where people are dying left and right. Moreover, I became a character with the lowest survival rate, a girl with no dreams or future! “The culprit is that person!” Unable to witness people dying in front of me, I subtly pointed out the culprit a few times. “Become my daughter.” The protagonist of this novel, who catches criminals, and also the most powerful figure in the Empire, the Duke, proposed adoption to me! Is the life in the back alley with an empty stomach finally over?! Even rejoicing at being allowed to eat two fluffy breads, the hidden settings of the novel suddenly come to mind. ‘…Wait a minute. Wasn’t the protagonist in this novel supposed to be a psychopath?’ The Duke, colder than anyone to villains, but warm to his adopted daughter!