Believe it or not, but people like this actually do exist. These are the ones that can dip out of Doctor Who at their own leisure because they're not an avid follower of the ongoing liaisons of TV's favourite Time Lord. Not yet, at least. They'll make a conscious effort to watch the series premiere, rejoin the party for the finale and then skip everything else in between. It doesn't really matter when they watch it, though, because, like they said, they're casual. They're always intrigued when a new Doctor steps aboard the TARDIS, too, so they'll tune in for their first episode to see what all the fuss is about. Generally speaking, they enjoy Doctor Who but not enough to become completely invested. The only thing stopping from them taking the leap from casual viewer to hardcore fanatic is seemingly the fact that they're able to differentiate between what's real and what's not. Lucky them, eh? A casual viewer is always happy to converse about Doctor Who but you'll probably lose their interest when you start to analyse the Underlying Themes. Just make a comment about how David Tennant's hair is "awesomesauce" and you should be OK.
Dan Butler is the Doctor Who Editor at WhatCulture.com. When he isn't writing his own articles or editing other people's, he can be found trawling the internet for gifs of Steven Moffat laughing. Contact him via dan.butler@whatculture.co.uk.