Tony could command him to do a lot of things. Anything, maybe, depending on the audience. It was how their dynamic was supposedly organized, Tony in control and able to push, pull, demand, or simply expect, and Jarvis ready to fulfill. He was the help. No, not even the help- a belonging, more useful than an appliance or the cars, but only because of utility. Jarvis only lacked a tongue, after all. He had two hands and two feet and a willingness to do damn near anything if Tony asked, but they'd more or less forgotten how to fit those roles unless someone was watching. Then, it was more lip-service than anything else.
Still. Tony couldn't tell him not to be afraid. It wasn't a command Jarvis could follow. He could want to. He did want to. But fear wasn't easily shaken in the face of something this big and awful, so far beyond Jarvis' ability to exert even the tiniest amount of control. If this took Tony out of the house, Jarvis couldn't follow. He'd sit here, nothing but furniture and towering walls and breathtaking views, and have to wait.
In a perverse way, someone turning up to shoot him might be a mercy, then. Jarvis wasn't sure he had enough courage to do anything, himself.
Thoughts like that tumbled over, petty and horrible, not quite drowned out by the familiar rhythm of Tony's breathing or the way his own heart hammered in his ears. Don't be scared. He couldn't be so lucky, to be able to turn that off like flipping a switch.
"I don't think I can help it," Jarvis admitted, trying to find a sheepish smile. It didn't hurt quite so much if he framed it like a failure to follow a command. Then it just seemed like a joke, albeit a poor one. He reached up, fingers curling around Tony's wrist. If his grip was too hard, at least he'd been given a good example a minute ago. They'd both wear finger-shaped bruises. It would be nicely symmetrical. "Don't leave me."