There is a predator that lives in the forest. It is roughly the size of a large bear, and moves quite slowly - a person could outrun it at a light jog. Nor is it agile - although its arms and jaws could easily crush a human once it has a firm hold of them, a person would have little difficulty slipping out of its clumsy grasp.
The reason this predator is dangerous is because its prey does not perceive it as a threat until it is too late. Somehow, it causes nearby animals to completely lose their sense of fear, which allows it to slowly nuzzle up against them in a big, furry hug before crushing their bones.
Is such a creature plausible?
I am assuming that the only way of achieving this would be for the creature to produce some kind of chemical or airborne drug. Is there any real-life chemical that could produce such a response quickly enough for this predator to catch prey?
If possible, the chemical should have as few side effects besides the removal of fear as possible; its victims should behave more or less normally, aside from the fact that they aren't concerned by this giant furry beast wrapping its arms around them.
The question is more about the gas than the creature; whether or not such an "anti-fear" chemical exists or can exist.
The chemical does not need to be strong enough to make the victim ignore pain; once the predator has a firm grasp it can continue squeezing or biting until the prey dies. It only needs to not be resisted while it's getting the grasp in the first place.
The effect should work on humans, but should not be exclusive to humans.
The creature does not need to be actively roaming; it can sit in a thick cloud of its own gases and wait for prey to stumble into it. But it's too slow to be a proper ambush predator; even if it snuck up from behind, without the gas the prey would quickly jump away in alarm the moment it felt the creature's arm starting to wrap around it.