So I imagine Addie definitely is completely skeptical about Mort's ability, because she doesn't exactly believe in anything supernatural at all. When Prince is running him over with cars and things, I'm sure Addie is watching trying to figure out the trick. Until she gets tired of the effort and just admires the showmanship...
As a former sister to four, Holly loves wild boys. Depending on their chemistry she's likely to either big sister him, or to join in the fun of watching and goading him to do his thing.
John will be morbidly amused by Mort's talent, but otherwise glare. He doesn't like Happy-go-lucky. Or tumbleweeds. Or anything else, really.
Verona will probably be fascinated by Mort. She takes an interest in anything otherworldly or strange. She's kind of hard to get through to on a deeper level, but she's got some tumbleweed qualities, too, and will talk to anyone.