Chell’s pretty sure she shouldn’t trust the little gargoyle. He seems harmless, and he TRIES to be helpful. He’s the first ‘living’ thing in Aperture Castle that hasn’t been actively trying to kill her. Maybe that’s what unnerves her. She doesn’t believe anything from this place can be truly friendly, but she doesn’t have much choice at this point. He broke the sleeping spell on her and he claims he knows how to get out of the labyrinth. If all else fails she still has the Portal Staff and her Long Fall boots.
But she’s still careful never to speak to him. If they never hear your voice, they can’t steal your soul.