[Autumn]

Sure, even though the act of Castling means swapping pieces around, it'd be more immersive if you could just peel for one of your allies. It'd give the Black Knight in question a more 'guardian'-esque vibe to always be there within range of a friend, or into combat with their allies who rushed ahead.

Nerf the Black, buff the Knight.

In that sense it still retains the chess vibe, as the rook moves beside the king, and you are using your allies as 'pieces' for your movement.