Sometimes you go into a movie with a very specific set of expectations. With a horror film, it's reasonable to anticipate that there will be a certain number of frights, maybe some jump scares thrown in. Some characters will survive; some won't.
Either way, you're not likely to have a lot of good feelings, and certainly not the kind of swoony, heartwarming emotions that come from a sweater-wearing ghost hunter dad singing Elvis to a group of kids (and, by extension, his wife who he is madly in love with).
Oh, hold on a second. Turns out there is a movie that fits that description and it is 2016's The Conjuring 2, a follow-up to the 2013 that sees Patrick Wilson and Vera Farmiga returning as married demonologists Ed and Lorraine Warren. After being called to London to investigate an evil poltergeist tormenting a single mom and her kiddos, Ed takes it upon himself to pick up a guitar and launch into an Elvis song (if only to cheer up the children, since poltergeists don't thrive as well in a happy home).
Besides, everyone knows that when you have Patrick Wilson in your arsenal, you'd be CRAZY not to find a way to use the dulcet tones of his singing voice. (According to an interview with Wilson, this was actually the first scene that director James Wan wrote for this sequel, so now we know exactly who to thank.)
I'm not sure who or what possessed The Powers That Be (read: Wan) to turn The Conjuring 2 into the GD Sound of Music, but I'm not mad about it.
Neither is Lorraine, if this scene is any indication. (That's an "I know we already have a kid at home but maybe we can make another one soon" face, for the record.)
If they weren't already married, I'd be convinced this is the equivalent of the moment where Maria and Captain Von Trapp fell in love while he performed "Edelweiss," only instead of going off into the sunset to hunt Nazis they hunt down evil spirits and live happily ever after.