For dashboard osmosis: Supernatural, mwahahahaha! (This is so unfair, my representation of it is so destiel-centric it has undoubtedly given a deeply skewed view, but that's fandom for you, lol!)
My Supernatural osmosis goes back pre-tumblr, I'm pretty sure, but sure, let's give it a go!
Second generation vampire hunters hunt demons and shit. The older brother had to do all the parenting of his younger brother when they were children; also, their mom was set on fire and pinned to the ceiling like a bug when the younger brother was a baby. Both of these events (and possibly also a run of dead girlfriends) have given the brothers epic levels of manpain. The younger brother has Giles' job. Unlike Buffy, the brothers do not have a local Hellmouth; they are on a neverending roadtrip in a Chevy Impala. (Except at some point they do acquire a "Bunker" so presumably they stop roadtripping at some point?)
The show suffered from hard-core misogyny charges at the beginning (see the dead mom and girlfriends), but I eventually stopped hearing about that. I was never entirely clear on whether this was because the most vocal objectors stopped watching, or if the show eventually managed to beat the allegations by bringing in cool women characters and refraining from fridging them. (I do know they brought in cool women characters! I especially like Sam's Deaf girfriend, and also the redhead that runs Hell. Plus also whatshername from Dr Horrible's Sing-Along Blog is there. I assume she's cool, too. Also, the brothers' mom eventually got unfridged! Back-from-the-dead mom is young and hot and MILF, because old women are icky, amirite?) I suspect but cannot confirm that a bunch of these cool women characters eventually got fridged, though. I am pretty sure most of them were only around for a season or so.
For the first several years, the main ship was Wincest, the aforementioned vampire-hunting brothers. Because of the writer's strike, however, an angel was brought into the main cast, and Destiel eventually came to supercede the Wincest ship in popularity. Destiel even became canon for one hot nanosecond near the end of the show. But then Castiel experienced a moment of perfect joy, and like Angel before him, lost his soul went straight to superhell.
Oh, and Castiel has a baby angel at some point? I think his name is Jack? Like Connor before him, Jack spends no time as a baby and is an insta-teenager, presumably to save on production costs.
Other things that happen to Castiel include losing his powers and becoming human. I'm not sure those two are actually related: the depowering was a gradual thing, and the becoming human seems to have been a sudden one that only lasted a few episodes.
Christian mythology plays a big part in the overarching cosmology until the whole thing hooks a hard left turn at the end, and it turns out God is a washed-up novelist. I don't even know what's up with that, this shit goes by on my dash and people assure me it's true.
Eventually the older brother gets impaled on some rebar and goes to Impala Heaven. The younger brother gets a wife who has no name and no face and lives happily ever after in the space of a video montage.
THE END, except for the spin-off about the boys' dad, which we do not watch because the dad is awful.