Diego can absolutely roll with crazy Russian girl flirting. But if she starts talking to him in Russian he's switching to Spanish. How long can they pretend they can understand one another? Who knows.

Then Reid probably likes her! He honestly does like people, so if she's friendly he'll just go silently take the spot next to her in Archery and let her talk at him. He'll open up with a little effort, but Reid opening up is kind of... jumbled. He's bad with words.

WELL if she tries consistently, he'll be a little warmer. He'll always have those sharp edges, but he won't irrationally think Katya hates him!