Guilt as a motivation.
For the tenth time of the morning, Shirou's shinai flew from his hands and clattered to the floor some ten feet away. His wrists stung from the blow, and the already-forming ache in his muscles promised a truly torturous ordeal when he attempted to move tomorrow.
"That's enough." The giant of a man standing on the polished floor of the dojo lowered his weapon and offered Shirou a hand, pulling him to his feet with ease. The sunlight outside signaled noon, and Shirou's stomach growled at the sight of the bento boxes he'd left by the door that morning.
Wiping the sweat off his face with a towel, he collapsed unceremoniously against the wall, pulling lunch towards him and handing one of the boxes to the giant who settled silently down beside him. It still never failed to amaze Shirou how quietly the man could move, given his size. "So, um, can we keep training after lunch?" he asked hopefully.
"Not if you want to be able to walk tomorrow," replied the hero, around a mouthful of tuna. "You're pushing yourself too hard."
"But if we're attacked---"
"If we're attacked, you stay behind me." Emphasizing his point by rudely pointing his chopsticks at Shirou's nose, he continued, "Do you have some sort of deathwish or something? You're trying to improve, and I certainly respect that, but you can't think that you're going to hold up against a Servant or even a normal sorcerer, do you?"
"I just want to be useful."
"You're most definitely not useful dead. What are you trying to prove, boy?"
"Nothing!" retorted Shirou, indignantly.
"Make up for, then?" Gentle amber eyes regarded him beneath bushy brows, too knowing by half. It made Shirou pause as he opened his mouth to deny the question, as he saw for an instant the screaming faces in the fire, clawed hands grasping for life and eyeless faces glaring at him in accusation.
The giant shook his head, and the deep baritone of his voice was not unkind as he spoke. "It's not worth it, trust me. Whatever you do, you can't change the past, and the only one who decides when enough is enough is yourself. Not that I should talk," he added.
Shirou poked his rice for a few moments, before answering. "I don't know. All I know is that I won't, I can't just stand there and let people get hurt."
He was rewarded by an exasperated sigh. "Alright, fine. But realize that you need skill to back up that kind of talk. I'll do what I can, but only if you fight by my rules. You may think nothing of risking life and limb but there's a number of people here," he gestured in the direction of the living room, where Fuji-nee was napping, "who'll be less than thrilled if you get yourself killed. Fair?"