"Oh, sure, it's super fun!"
After realizing what he said, and then hearing what she said, he took a bit of a giggle out of it, being the pervert he was, but tried his best to stop laughing as he took a deep breath to calm himself. He was a bit surprised she took it so innocently. That, or she just ignored it, but he didn't mind because he sort of liked how innocent she was, seeing how he was a bit of the exact opposite. Not as in his pervy personality, but from how dark he would be at times.
'You liar...'
Shirou seemed to have sighed to himself tiredly, thinking of the past again but shook his head immediately and told himself that it wasn't important and just did his best to ignore it. His dark personality always showed, especially in the mornings as seen when he woke up from his nightmare, but he didn't want to think of it, or let anyone else discover it, so he hid everything with a mere smile on his face as he always showed.
"Well, hopefully we do get a new mission. I've been dying to take on a new one ever since last time! It's been way too long, don't you agree- Hey, are you alright?" He noticed his partner was slightly tense, and wondered if it was anything he said, and he think he knew exactly what made her so uncomfortable.
He sighed and patted her on the shoulder before saying, "I was just joking, I was just joking. Sorry to scare you, dear! But honestly, do you think someone as great as me would get hurt that easily? If that was so, then all the girls would probably be crying their hearts out! I just simply can't let that happen!" He said dramatically.
It wasn't exactly what he meant to say, seeing how he had trouble comforting other people. What he really meant to say was an apology and probably try to say that he wouldn't die because he had the will not to, but he wasn't the type of person unfortunately, as much as he wanted to be, so he could only say what he was able to say, as an idiot pervert.