Tsireya would be cautious towards him initially for obvious reasons, but he's connected to Lo'ak at the hip, and she sees firsthand that Spider is one of them. Caution gives way to curiosity, and before you know it, Tsireya is spending time with Spider, asking him questions, counting his five fingers, encouraging him to try a new hairstyle (because those dreads aren't it), teaching him how to properly use a net, etc. Humans are so teeny and it's hilarious playfighting with Spider because she gets to lift him up and watch him squak and flail his limbs. She even teaches him how to properly swim and hold his breath for long periods. Even better if Norm shows them baby pictures of Spider and Tsireya is cooing over one picture of toddler Spider running from bathtime.
"Human babies are even tinier!"
I need Spider to make friends outside of the Sullys. It feels like we only ever see one side of him because he's always around Neytiri's children and can never truly be himself without raising suspicions or anger. Making new friends beyond the Sully inner circle would give him the freedom to be unapologetically himself, and Kiri would start to notice just how bright and mischievous he really is. Spider is still a teenager, and I want him to act more like one: childish, bratty, sullen, and explorative, the way all teenagers are supposed to be.