Double-Edged Knife

Eric realizes Four's feelings for Tris at the start, and is attracted to Tris as well. Seeing this as another competition, to win her over before Four does, Eric takes her under his wing, personally training her so she could make it through stage one, not realizing that he will start developing feelings for her. Meanwhile, Tris becomes gravitated towards him against her will. No one could possibly develop feelings for an ruthless Dauntless leader, right?