The Story of Shen
Shen is the Eye of Twilight — the leader of the Kinkou Order, the position his father Kusho held before him, responsible for the Order's most difficult function: maintaining the balance between the spirit world and the physical world without allowing emotion, attachment, or personal interest to compromise the assessment. He inherited this responsibility at enormous cost. Zed, his childhood companion, killed their father and shattered the Order. Shen rebuilt it on the original principles.
He has mastered something that most people cannot approach: the severing of emotional response from action. He does not eliminate feeling — he contains it, observes it, acts without being driven by it. This is the Eye of Twilight's specific discipline. He watches as much as he fights, understanding situations before intervening, intervening with the minimum force that addresses the imbalance rather than the maximum force that expresses his feelings about it. He is one of the most dangerous people in Ionia. He is also one of the most controlled.
The cost of this control is visible to people who knew him before. Zed knows what Shen is suppressing. Kennen knows what maintaining the Eye's discipline costs. Akali left partly because she could see the price and decided it was too high. Shen continues because the Order requires the Eye to function as the Eye, not as a person with preferences, and because he believes that the discipline — however much it costs — produces better outcomes than the alternative. He may be right. He has not allowed himself to fully test whether he is wrong.