Fear currently has what we call a "heartbeat resist check" - meaning, it can take some damage or no damage or a lot of damage before it breaks. Generally, it works that the more damage it takes at one time (e.g., direct damage), the more likely it will break. However, because of the heartbeat resist check, it may or may not break with any damage taken at all (this is one of the reasons people don't like Fear cc much).
Jenova is correct, though; the mechanic is being changed such that Fear is getting an actual damage cap, a percentage based on the target's maximum health.