This entire scene told me a lot.
First note that Emma and Killian really enjoys his rum. In the end, Killian really cares about Emma’s relationship with her parents. He knows that she won’t go dark but he also knows she’ll regret letting her spite for their betrayal make them leave her. He understands her parents and tries to get her to understand why they did what they did. He can understand wanting to make Emma happy and proud. He knows she doesn’t want her parents attempts to be failure. Emma was also very stubborn in this scene. She really didn’t want to hear what Killian was saying because she knows deep down he was right. Then she tell him she would’ve accepted them and liked them more if they had told her the truth. She likes watching people find their good hearts. She looks at him with a smile when she says that. She always gets a proud smile when they talk about his change or accomplishments. She likes how much Killian has grown. She likes that he worked on it instead of pretending to be someone he wasn’t. She knows how much he worked on finding his good heart and acknowledges it. Then Killian is bashful. He always gets that way whenever he is given praise. He didn’t really know how to respond to it. He just gave her a smile and went back to what mattered. All he wants to do is protect her heart/happiness and that is why he tried so hard to get her to listen. Also when he says he wants it to be his job to protect her heart, she didn’t protest or confront it. She isn’t bothered by it or have any issues with Killian trying to protect her heart whether physically or mentally. Then after everything had been said they just soaked in the conversation and continued to let the horizon calm them.
(Gif created by emmakillian)