Kylo manages to overhear Phasma praising Hux's magical hands. (Note: I can't imagine Phasma saying that out loud so go ahead and have her projecting her thoughts and Kylo hearing loud and clear). It leaves him silently sputtering and panicking until her thoughts reveal that she had another fantastic massage at Hux's hands. Kylo's training and missions often leave him worse for wear. Bacta is always needed for more serious injuries but wanting to keep his body mostly chemical free he has never done anything for general pain. And perhaps the General can help him with that. Next time he meets with Hux he mentions he's heard about his massages and wants one himself. Demands it, despite Hux's attempts to say no and persuade otherwise. When Kylo finally has his session he's first treated to hot rock therapy massage. He's all relaxed, unbelieving his luck. Then Hux moves onto his main specialty. Deep tissue massage. From then out - go wild. Shock. Pain. Tears. And how can such a limp pencil pusher cause him so much agony? But pain does lead to the dark side so maybe this isn't all that bad. Hux/Kylo optional.