While growing up among the Blades, Keith always had a rather distorted perception of their fight against the Galra Empire, and he only realized that once he finally joined them. So a big part of Keith’s character in this au would be his right morals clashing with the Blade of Marmora’s practical objectives. And that’s at the base of him saving Shiro: despire it not being contemplated in the mission, this act is a way to show Kolivan that they can carry on a good war strategy without neglecting innocent lives.

Basically, the only reasons Keith saved Shiro was a) to prove his point to Kolivan after years of being silent and following the Blades’ philosophy (mission > individuals), and b) because he could, so he did. And the only thing Shiro felt for Keith was gratitude for having saved him from Zarkon’s Arena. So, from this alone, there is literally nothing that could hint to the fact that the two are going to fall for each other.

Anyway, right when Keith brought the Champion among them, Kolivan just fucking KNEW those two bastards were going to fall for each other jesus christ he just KN E W.

The Blades never hid their scepticism towards Keith’s half human nature, and he had always felt a bit out of place among them. Getting to know Shiro better also means getting in contact with another human being and therefore with that part of himself he had long tried to suppress.

Shiro can’t (and tbh doesn’t even want to) become a Blade, but since Keith’s initial excuse for saving him was that he could be of use to the team, he trains with them. Them is actually just Keith, who teaches him how to fight (cue many sessions of them training which include TONS of UST because that’s my jam)

But Shiro joining the Blades isn’t just an act of gratitude towards his savior(s): he just really wants to find and rescue Samuel and Matt Holt from Zarkon. And as they grow fonder of each other, Keith will help him in his (kind of secret?) purpose.

Before they get to know each other, in this au Shiro and Keith argue more than in canon verse (I mean, we haven’t really seen early Shiro and Keith in canon verse yet so who knows). On one side you have Keith, brought up in an environment that he’s never really felt a part of; on the other, Shiro has just been rescued after what could have been months of fighting as a gladiator against specimen of all kinds. I just picture both of them as really difficult, clashing personalities, closed off emotionally and all that jazz.

Since Shiro was impromptu saved by Keith, Kolivan made it clear that he was going to be Keith’s responsibility. That also meant that he was supposed to share his quarters with him.

The two points above are functional for what I believe would be a crucial point in the development of their relationship in this au, which is: Shiro confronting with a sudden crisis due to his PTSD (possibly triggered by a mission to which he has taken part on the same day? But Shiro would ignore his feelings until the mission is completed and the team arrives safe on the ship). So Keith is also the only one in the room witnessing his agitation, and he has no idea of what to do to help him through it, but he tries to. And it’s more than Shiro could ask for.

I don’t know if this can be considered an headcanon but if a fic was ever to be written about this specific version of champion!Shiro + BoM!Keith, it would be called An Act of Kindness because Bastille hold the key to my heart and that song = this au 10/10

(I definitely can’t make myself more ridiculous than this, so) this is a glimpse into the mess that is my head when it comes to this au. I have a couple more scenes that randomly flash before my eyes (like their first and second kiss and some other pivotal moments for their relationship) but they’re so volatile there’s no way they’re going to make any sense if written on here lol