Responses
Prince. They have a better knowing of each other than the duke. The mc and prince have known each other (and were close) when they were children. Also, the prince cares a lot about the mc and where has the duke been when the mc was having a rough time eating and sleep? The prince is caring with the mc. Also, the prince and mc are on the cover of this ^^
Duke or Prince?
Don't be bias just because the Prince appears so many times compared to the duke.