how do you think chanbig would propose to each other? 👀
Oooh, this one is hard since their screentime is limited, so I am going off of what we have seen/fanon/personal headcanon.
I think Big's long-term unrequited love for Kinn likely made him feel slightly undesirable for a while. In a universe where he and Chan live through the close calls from their injuries, heal together, and become very close, there would likely be an adjustment period for both of them. Big is in love with someone he has known, cared for, and trusted for a long time who ISN'T Kinn. He feels so safe with Chan. As for Chan, he is extremely guarded and spent his life dedicating his time to another family. Loving Big almost seems selfish at first.
However, once Chan pulls himself out of that mindset, he can see Big has been so touch-starved, desperate for love, and is very committed to this relationship. It would take a while for either of them to think of marriage. It only happens when Chan himself starts to open up more to Big and become more comfortable being more openly loving and expressive with his affection. I think Chan knows of Big's past unrequited feelings for Kinn, but he can see that they aren't an issue. Big is now in love with Chan, and he is likely a bit clingy at times. It's almost as if he believes Chan may change his mind, pull away, or announce that Big misunderstands Chan's true feelings. Even under the slightest disagreements (usually occuring because Big's insecurities get the best of him or Chan getting overly protective) Big needs reassurance.
While Chan never saw himself getting married, he finds himself liking the idea of taking that step with Big. While there are a few concerns (falling more deeply in love and the strengthening fear of loss due to their lifestyles, the age difference, etc), he decides to take that step. He finds Big a subtle but tasteful ring, and plans a proposal.
The thing is, Chan isn't the best with words or romantic gestures. They aren't necessarily his thing. He expresses his love through acts of service and comfort. The only thing Chan can think of that won't come off as completely out of character is taking Big on a vacation to a relaxing location he has always wanted to go to. He wants to make the trip about Big, become closer with him, and when the timing feels right, he will ask.
The timing never feels right. There are opportunities at romantic locations, but Chan gets uncharacteristically nervous and doesn't pop the question. It only feels right on their last morning there. They are watching the sun rise on a beach. Chan glances over and is hit with SO much love when he sees how content and peaceful Big looks, then digs into his pocket and pulls out the box. He takes Big's hand, puts the box into his palm, then lets go as he looks at the sunrise again.
"Your call."
Big is shocked. He's delighted, but he's shocked. And for the first time, he needs to hear the words. He needs that clarification and says as much.
"I need you to say it. Please."
Even though it is hard for Chan, he can't deny Big of any request he makes, especially as something as simple as this. It feels extremely hard to say - harder than anything he has ever done for the major family - but Chan logically knows it is so simple. He loves Big and wants to commit himself to him.
"I love you. I want to spend whatever is left of my life with you. Will you marry me?"
The answer for Big is just as easy. He doesn't hesitate in saying yes. They both let themselves smile in a way they were no longer sure they had the ability of, and they extend their trip for another week because they now both know they deserve it.
Thank you @chanbig for the ask! It was so interesting to answer!