Snake is surprised to see her so close so suddenly. Just when he had given up on her showing interest, she didn't only nearly trip over him, but just said hello so cheerfully.

His eyes grow wide and the eels scatter as he quickly dips back under, quickly swimming away as his tail briefly nearly breaches the surface. A moment later he peeks back above the water about fifteen feet away, watching her carefully.

She'd not said anything mean despite the fact that even his human half is covered in eel scales. She just asked if he had been there the whole time. Did he really need to run away? He doubted he really did, and he still wanted to learn more about the humans that liked to show up all around his lake.