Reminiscing is nice...try to talk of endearing times, funny times, just anything at all. If he can blink you can create a system for yes and no responses from him. If he can squeeze your hand, the same thing applies. Assume he has itchy spots and hot spots and try to do for him, like turning and fluffing a pillow, or using a damp cool cloth to sponge his neck and face...use your imagination. If he can give a yes or no response you can use it to find out if and where he hurts, itches, is too cold
or hot, etc. He's in there...and family can do wonders for him.