You become obsessed with one Survivor.  Your Obsession gains a 33percent action speed bonus to unhooking and healing other Survivors.  Each time you hook a Survivor other than the Obsession, if the Obsession is alive, gain a token.  If the Obsession is alive, all Survivors who are not the Obsession get 3percent penalty to repair, healing and sabotage speeds for each token.

When hooking a Survivor, all other injured Survivors suffer from the Hemorrhage and Exhaustion status effect for 45 seconds.

Blood Echo has a cooldown of 60 seconds.

Exhausted prevents survivors from activating exhausting perks.
Hemorrhage regressing healing progress when not healing, and increases blood trails left by injured survivors.

The Scratch Marks left by Survivors spawn slightly/moderately/considerably closer together.

Crows startled by Survivors within 20/28/36 meters alert you with a Loud Noise Notification.
Spies from the Shadows has a cool-down of 5 seconds between alerts.