[WARNING: The following contains spoilers from Sunday's Once Upon a Time winter finale. Read at your own risk, dearie!]

On Sunday's midseason finale of Once Upon a Time, we finally got some insight into why Killian Jones, aka Captain Hook (Colin O'Donoghue), had a penchant for evil in his past. As with most villains on the show, he was terribly hurt by a loved one. When we meet cute little Killian in a flashback, he had freckles, both of his hands and a devotion to his dad (Adam Croasdell). Unfortunately, that faith was unfounded. After glib words about being brave and deciding what kind of man you wanted to be, Papa Jones sold Killian and his brother Liam into slavery in order to get out of a sticky situation. Yeah, that's pretty messed up.

Fast-forward to grown-up Hook, a dashing drunkard who makes a deal with Evil Queen Regina (Lana Parrilla) to kill her mom in exchange for her bringing him to a land where he can finally get revenge on Rumplestiltskin (Robert Carlyle). Again with the revenge! But first, to prove he's worthy of matricide, Hook must commit patricide. Yep, Regina brings Hook to his dad, who's been slumming it as a barback and apparently hasn't aged a day in over a century. Abandoning your kids is great for the skin!

Regina's dad is returning to Once Upon a Time

Despite the lack of wrinkles, Papa Jones is a changed man. He was under a sleeping curse but was roused by true love's kiss and therefore knows what it is to be good. Anyway, it's enough for Hook to spare his dad, but fake his death because of course nothing is that simple. But then, Killian realizes that his dad has had another son, his half-brother, whom he named Liam - the same name as the boy he abandoned. That really chaps Killian's hide, and so he decides redemption be damned and kills his father as planned, stabbing him in the gut.

Back in Storybrooke present

In Storybrooke present, the gang discovers that all of them -- except for Dark Swan Emma (Jennifer Morrison) -- have glowing insect tattoos on their wrists. It's the Mark of Charon, the ferryman of the Underworld, which means all of the Dark Ones past will switch places with our heroes, damning them to a lifetime of torture. Instead of trying to fight this horrible fate, the gang (except Emma and Regina) decides to party it up with their loved ones at Granny's diner. Shop local, guys.

Meanwhile, Regina realizes that trying to trust Zelena (Rebecca Mader) as a new mom to Baby Pistachio Hood was a really bad idea (ya think?), so she breaks out her wand and sends her Wicked Sis of the West back to Oz in a green twister. Which she should've done last episode. But whatevs.

At Gold's shop, Rumple gives Belle (Emilie de Ravin) something that will protect her while crossing the town line so she can see the world and then later gives Emma Excalibur because she has a scheme to use it to take all of the darkness into herself and then destroy herself. Once a savior, always a savior! But then again, she got them into this mess in the first place. Dark Hook is still really butt-hurt over Emma turning him dark though, and wants Excalibur for himself so that he can make her watch everyone she loves die.

Once casts Greg Germann in a devilishly mysterious role

The S.S. Purgatory arrives to gather our heroes on their trip to the Underworld, but just in time, Regina echoes the words of Killian's dad to him: What kind of man do you want to be? This is enough for Hook to break free of the darkness' hold on him. You can tell by the muscles working overtime in his jaw and temple. He enacts Emma's plan, using Excalibur to suck up all the darkness from the Dark Ones, himself and Emma. Then, in the most messed-up sacrifice ever, Emma uses Excalibur to kill him, the man she loves. It's actually pretty heartbreaking to see them embrace as he dies. Even his guyliner looks like it's slid off.

Unhappily ever after

Emma, back to herself in red leather as the un-darkened savior, goes to Gold's shop because she can hear the dagger still. What? Rumple looks super-happy, which we assume has something to do with reuniting with Belle the previous night. But oh, no, it's more than a little nookie. He's feeling puckish because he's the Dark One... again. It turns out that he bespelled Excalibur so that instead of absorbing all of the darkness, it channeled it to Rumple, who is always power-hungry.

The dog days are over! Cruella de Vil is returning to Once

That means instead of sacrificing himself to get rid of the darkness, Hook sacrificed himself on the basis of a lie, which really, really sucks. Naturally, after being forced to kill the man she loves, Emma is not pleased at all. She makes Rumple call the ferryman so that she can go to the Underworld herself and save Hook. "Hook, I will find you," she promises, all Last of the Mohicans-style. "I will always find you."

Well, hell! We knew that Once Upon a Time was going to Hades, but we didn't foresee this. What did you think of the episode? Did you cry for Hook? Share all your thoughts below.

Once Upon a Time makes its hellish return on Sunday, March 6 at 8/7c on ABC.

VIDEO: The Once cast shares their character's happy endings