Don't mind me just placing my BS thoughts here ...
With the way how Sun was introduced i think he was always meant to be by Blake's side; he's usually around whenever the white fang is involved and the white fang is a big part of Blake's character and what shaped her into who she is for both the good and bad.
In volume one he's the first person Blake opens up to and goes to investigate the white fang with her.
He was paired with Blake to investigate the white fang in volume two.
(not white fang related but they were paired together for the dance too and spent majority of the dance together :3)
He goes after Blake because he thought she'd be going after the white fang.
He's in Menagerie right now supporting Blake with stopping the white fang.
There's a whole gotdamn song about Sun being there for Blake whenever she runs away or when things get tough
I feel like BS was supposed to be a ship that should've been developed earlier but got pushed back because of plot reasons however they've showed small..small..hints.
Blake hasn't shown any romantic interest in anyone besides Adam or at least acknowledges she had something with him but besides that the only other person she's shown or at least a VERY SMALL little baby interest in was Sun and that'd probably be the blush scene where she looked away trying to fight her growing smile off and blush when he pointed at her....may i also point out not fall in love with you was playing in the background during that scene (;
Sure Blake and Sun had some rocky times but Blake was going through an understandable hard time, and Sun just wanted nothing more than to help Blake and i don't really see it as him doing this because he likes her (okay maybe that too lmfao) but i think it's just in his nature to go out of his way to help people. They're both learning off of each other which has developed them both a bit...and the longer they spend time away from their teams the closer they're just gonna get.
I also think people shouldn't sink BS just yet because we don't even know much about Sun and why he acts the way he does, how his life was growing up as a faunus, there was a 'No faunus' sign shown on one of the shops in mistral and makes me wonder how many other places in mistral are like that, why did Sun go to Mistral academy and not Shade academy...i feel like his reasoning could've been similar to Weiss since she could've just gone to Atlas academy but she went to Beacon instead. There's a lot of things that could be said and done with Sun......I feel like the first person Sun is gonna open up to would be Blake if he hasn't already done that with Neptune .
The only question is. What are they gonna do with Sun when Blake reunites??? Will he go searching for his own team?? or will he stay with Blake and help out Ozpin??? Will he run into SSN at the battle of Haven?? so many possibilities...i'm sure he's gonna be around if it has anything to do with the white fang....but what then....