"Oh? Had I known I was in the presence of a baron, I would have gotten one of the better bottles from the kitchen."

See? He can joke. It just happens to be dry and deadpan through and through. It is a ridiculous story, one he didn't expect Lambert to believe in the least, but he isn't about to change it (until he asks again, then it will definitely be a different, entirely fabricated reason).

What he was before the carnival, though, now that does take some consideration. How to put it? He's still reluctant to go around claiming to be a magician, so that's out, which leaves, quite simply, "I was in the service of a magician prior to the carnival, thankfully the sort without monsters being involved."