"Blood Brothers" is the long-awaited vampire origin story of Stefan and Damon Salvatore, so hop in my DeLorean, because we've got to go back in time.
Previously, on The Vampire Diaries: For over a century, Crittertarian-Vampire Stefan Salvatore lived in secret, but now he has to know her, i.e. Elena Gilbert, dead ringer for vampire Katherine Pierce. Stefan takes a flying leap off the roof of Mossy Manse and into the sunshine of Elena's love. In flashbacks to 1864, we learn that while Stefan and Damon each want exclusive rights to Katherine, she's the one who makes the rules, and is quite sure that choosing drools. After Papa Giuseppe Salvatore spikes Stefan's drink with Vervain, Katherine feeds off Stefan during their assignation -- and is instantly incapacitated. Papa bursts in the bedroom and orders Stefan to get the sheriff, who returns with a torch wielding mob. Katherine, now wearing a Hannibal-esque mask, is promptly tossed into the back of ye olde paddy wagon. Damon begs the mob not to take her, but his father pulls him back, warning that if he's linked to the vampires, he will be killed along with the vampires. Stefan promises Damon they'll get Katherine back, to which Damon is all is this fail not already epic enough for you? More recently, Stefan is back on human stuff, from both blood banks and nubile necks. He's not fussy; and he's not sad. HE'S HUNGRY! He tells Elena that human blood brings out the beast within. Elena refuses to listen. She's not going to give up on him. After she gets all hot and bothered with Damon on the dance floor, she stabs Stefan in the back with a Vervain dart and slaps his ass in the detox dungeon formerly inhabited by Damon.
Mossy Manse; Present: As Stefan drifts in and out of consciousness, a single perfect manly tear forms in the inner corner of his left eye. Who does he think he is -- Dean Winchester?
1864: Stefan and Damon Salvatore watch from the bushes as Johnathan (sic) Gilbert the Elder (Joe Knezevich) leads his torch bearing mob through Mystic Falls, following only the bearings on his ACTUAL VAMPIRE COMPASS. The mob puts a Hannibal mask on a young male vamp, we'll later learn is Henry. Gilbert yells out to the men: "We have to get to the church; they're waiting." While Damon flanks them, Stefan pops out of hiding and yells to the Goons: "Over here. There's another one. Quick!" Once the Goons run after their red herring, Damon disables the paddy wagon guard. Stefan then doubles back from the red herring hunt, rejoins his brother, they unlock the wagon and get Katherine out. Rather than rushing her to safety, they stay right in the very spot to which the Goons are most likely to return, and remove her mask, because they're too dumb to live.