Hayley made a disturbing discovery about the Hollow on The Originals. While taking Hope to visit her grandma Mary in the Bayou in "I Hear You Knocking," Hayley learned that her family might have a connection to the dark spirit currently going after Hope and infecting Klaus and Marcel. With Mary's help, Hailey discovered a family connection to the Hollow on The Originals, and it's not good.
It turns out, Mary has come across the Hollow before, specifically the sigil of the snake eating it's own tail. It was drawn in her husband's journal just before he went mad and killed Hayley's parents. If the Hollow forced Mary's husband to kill Hayley's parents, it stands to reason that the Hollow could want Hayley dead too. In fact, Hayley thinks that the Hollow might just have a grudge against her entire family. Hayley doesn't know a lot about her family, the Labonair werewolf bloodline, but she does know that they have a history of bad luck and were known to bring destruction and death wherever they went. Could the Hollow have been responsible for the death of the Labonair family? And, if the Hollow was after the Labonair family, is that why the dark spirit seems intent on killing Hope?
If the Hollow really is after the Labonair bloodline, then that means that both Hayley and Hope are targets. It also means that the Hollow infecting Klaus and Marcel was just one part of a larger plan to exact revenge on Hayley's family. Freya may have been able to get the Hollow out of Klaus and Marcel, but it's not gone for good. The Hollow will be back, and this time it might be going straight for Hayley.