I came to this revelation bc as have said Barclay is literally me and I began to notice that everything I am that Barclay isn't, Yasha was, and how that is mirrored in a lot of other places too!

For example:

1 ) Barclay's lore is mostly cold while Yasha's is hot

2 ) ^ similarly, Barclay usually wears cool/dark colors and Yasha usually wears warmer colors (at least in my head I associate him with red)

3 ) Barclay is pretty messy and wild while Yasha is neat and precise

4 ) Barclay leads with his heart first, often leading to reckless decisions, while Yasha leads with his head first and almost everything he does is calculated

5 ) Barclay is relatively short and (at least in my head) Yasha is decently tall

6 ) (my personal favorite!) Barclay has dog symbolism / associations and Yasha has cat symbolism / associations via their beasts and actions. Symbolism might not be the best word here (similarities might be better) but like, Barclay is generally a friendly person and very loyal to his friends (a trait associated with dogs/wolves) while Yasha is more closed-off and solitary (albeit forced to be by circumstance) which are cat like traits! I have further cemented this connection in my brain bc I have also read the Spirit Animals series (in which they have similar bonding mechanics), and in those books people tend to gain some physical ability and/or behavioral likeness of their creature.

And there's probably more I'm forgetting!