Giving an internal sigh, Theo pulls out Jasper. The rat blinks at Merlin with one eyelid and red beady eyes. It's also got a gash in its side and is missing some tail. Other than that it's a perfectly normal looking rat.

"This is Jasper. It's my minion," he says. "Say hi Jasper."

Jasper says hi by stretching out to try and touch noses with Merlin.