Hellhounds are dead dogs who were turned into Demons and serve their demonic overlords. Usually demons will go around and kill dogs so they can turn them into hellhounds for their evil benefit.
On May 6th, 2015 however, Felix found the dogs dead. They were decapitated, disemboweled, and still on fire. Their blood was used to spell "MikeNnemonic will cause pure darkness! You can't stop!". They were victims of Mikes evil deeds.
On May 8th, 2015, Mike revived the dogs in the form of Hellhounds to play mind games with Felix. The dogs began to kill some innocent people and RUC soldiers trying to defend the children from them.
After the incident, Felix regained his composure and promised he will put those hellhounds out of their misery.
Hellhounds are known to eat young virgins in order to become stronger.