The worst aspects of one of my fursona manifests itself as a man from his family's past. Here's what the entity looks like :
My fursona is Vsevolod "Dreva" Ingemann, a colonel in Israeli Air Force, a Mossad assassin and black op forces.
His shadow aspects is Rudolf Bauer, a colonel in Einsatzgruppen SS of Nazi forces who murdered Dreva's great grandparents during the Holocaust.
Both of them worked for special task force for their respective states. Both assassinated the enemies of their respective states.
In Dreva's case, the enemies are high-rank personnel of organizations that threatened the safety and existence of Israel and its citizens such as Hamas, Palestinian Islamic Jihad, Hezbollah, ISIS, Iran Revolutionary Guard, etc.
In Rudolf's case, the enemies are the Allies, the communist partisan, underground dissidents of occupied countries, and foremost in Nazi book, the Jewish people. For Rudolf and his superiors among Nazi bureaucracy, Jewish civilians were just as complicit as the Allies's combatants and as dangerous hence the need to "remove" the supposed threats.
The dark aspect of Dreva is that because he had killed so many people on behalf of his country, he starts to realize that he is slowly being desensitized to the lives he was ordered to do away. He is slowly becoming the man that murdered his great grandparents and the Jews of his ancestral hometown. He is slowly evolving to become the very horror that his grandparents described to him every Passover. And that chilling revelation continues to haunt him.
Just as the Nazi Rudolf Bauer, they both bore no personal hatred for the people they murdered. They were doing their jobs dispassionately without any blood lust. They held to their convictions that they were doing what was necessary for the sake of their respective countries and people. In their books, the lives that they took were merely number and targets. The lives of the people they were supposed to snuff out were slowly becoming statistics and achievements.
That's what I could think of for now. Hope you enjoy.