They are more than partners I'd say and definitely more than something we piloted at the Garrison. Black has been a good partner. And I wouldn't call someone who didn't try to break into a base to save someone only a partner.
[Yes, he remembers quite clearly Red trying to destroy the Blade of Marmora's base to rescue Keith. Yes, the lions has acted to protect them, but that... that still took the cake.
Shiro's also going to subtly lean a liiiiiiiittle out of the way to keep from getting hit by Keith]