Characters are assigned specific traits depending on their personalities. Canon characters have pre-determined fame types and you can select whatever you'd like for a custom character. In order to get a particular fame ending, it must be the highest ranking fame for your character. This is done by picking a character with that trait, as it nets you that particular type of fame after each victory. Skirmishes can offer an array of fame types, so keep an eye on this as you go on. It doesn't matter if you're a ruler or officer, whatever your highest fame rating is that will be the ending you see. After the credits roll and you are returned to the main menu, the trophy is yours.
Side note: I personally found it best to stack these trophies with maximizing a particular fame type, if you do both in one playthrough you could theoretically complete the game in approximately 6 scenarios.