Okay let’s break this down and go through it because honestly it works perfectly for Captain Swan.
Enemies
They meet when Killian is pretending to be a blacksmith, allied with Cora, who is definitely their enemy.
to Resentful Allies In A Time Of Crisis
They team up in order to climb the beanstalk and find the compass; Emma isn’t too happy about it, Killian delights in winding her up.
to Grudging Mutual
Respect
Emma betrays Killian, Killian betrays Emma, but they did make a pretty good team in between, and it seems that they’ve both met their match.
to Growing Fondness Concealed By Snark
Killian shoots Belle, Emma is exasperated but still helps hide him, snarks at him but then agrees to accompany Gold to New York in order to keep him away from Killian.
to Hurtful Betrayal
Killian steals the magic bean and sails away from Storybrooke. And Emma was so sure they’d had a moment and she’d got through to him.
Bloody pirate.
to
Slow Reconciliation With A Greater Understanding Of Each Other
Killian turns his ship around because he owes it to Bae, and Henry, and maybe there is something to this whole hero thing after all. Emma sees that, yep, there is more to him than just the pirate, after all.
to
Strange But Solid Friendship
They sail the ship together, and making their way through Neverland, and their moments involve him snuffing torches for her and asking her about his Disney alter ego but Emma always seems to stand very close to him and they trust each other and work together without even realising it.
to Unexpected Feelings In A Time Of Crisis
Emma kisses Killian, who realises that oh crap, he’s already more invested in this non-relationship than he ever planned to be; Emma’s magic flares to life when Killian is having his shadow ripped from him, saving him.
to Denying Their Feelings While Growing Closer As Friends
Emma insists that it was just a kiss, Killian promises to back off and tries to charm Tink, but somehow their eyes are just drawn to each other in every scene they share and they keep instinctively working together.
to Epiphanies
Of Love In The Worst Possible Circumstances
Oh no, everyone is getting ripped back to the Enchanted Forest and this might just be goodbye forever, and it hurts a hell of a lot more than it was supposed to, and he’ll think of her every day, and she kind of likes the sound of that.
to Mutual Pining
The entirety of 3B, pretty much, and in Killian’s case, also the missing year; it turns out that they are excellent at pining and longing and yearning, and getting more practice every day.
to
Unbearable Sexual Tension
The last few episodes of 3B, especially the finale; he can’t kiss her, she kind of wants to kiss him, she’s planning to leave, he really doesn’t want her to but can’t stop her, and then they get trapped in the past and there’s more teamwork and snark and flirting and then she does kiss him, only it’s the wrong version of him and he’s very annoyed, and they dance together, and she’s captured and she rescues herself which he finds hot as hell, and he comforts her when she cries, but nothing comes of any of it because she’s still holding back and he’s a gentleman.
to Lovers
He traded his ship for her, and she just realised that she has a real home now, here, with her family, thanks to him, and…