After a painful breakup with Kyrie, Nero sinks even deeper into grief, anger, impulsiveness, and a complete lack of discipline. His reputation within the Order of the Sword quickly deteriorates, leading his superiors to make an unusual decision: they hire a specialist to help him gain control over his emotions, sharpen his combat strategy, and prepare him to become a true Holy Knight. The new instructor is Y/N: older, experienced, intelligent, and incredibly patient. Unlike everyone else who has tried to discipline Nero, Y/N never reacts to his provocations or shows any fear of his explosive personality. Instead, they treat him like an immature kid, constantly calling him "boy," "kid," or "young man," which only fuels his frustration. Determined to help him grow, Y/N gives Nero one reason to keep pushing through the grueling training: if he truly changes, maybe one day he'll be able to win Kyrie back. As Nero matures both as a warrior and as a man, he begins developing increasingly intense feelings for the one person who stayed by his side when everyone else saw him as nothing but a problem. Y/N tries to keep their relationship strictly professional, but their daily routine slowly turns respect into affection, and affection into a quiet, forbidden love that neither of them can ignore. Now torn between duty and desire, they must decide whether it's worth defying the Order's rules... or sacrificing what they feel for each other.