More sad headcanon: Based on brief mention in the novels, Tessa had feelings for Bani, the Whispered boy who developed Al. Her cling to Sousuke isn't really about him so much as it's about his (irrevocable) tie to the last thing Bani made before the Whispers drove him to madness and, eventually, ending himself.
I’d believe this if not for the fact that her being drawn towards him started well before he knew the Arbalest existed... Though perhaps it could have added to her persistence













