Sebastian keeps his hand on the dogs back and firmly relays the 'down' command. It seems that at the very least, he's got a well trained dog who might not trust Severus but doesn't bear him any ill-will.

"The second war," he replies plainly. Sebastian is aware that there's never been any value in hiding the truth from any variation of Snape - either it's something he already knows and will accept as obvious information from a mooncalf idiot or it's new data and therefore Potter is lying. "I started young and we didn't have trained mediwizards."

He speaks slowly, taking care with his words, and while he'd prefer to make a good impression doesn't believe that such a thing is possible.