what species can/will feed off each other? (for demons, sirens, vampires, etc)
Vampires feed on faeries as a rare treat, because it gives them a high and overfeeding can cause blood insanity.
Vampires cannot drink from a werewolf, their blood is poisonous to them.
Werewolves only eat people, and only if they are driven to their highest animal instincts during their wolf period during the three days of the full moon. If you wanted to play a werewolf that did otherwise, feel free.
What sirens eat is unconfirmed in this world, so people don’t just know, they’re a rare creature. Some believe they eat human flesh, it is closer to a succubus type thing though. Just the opposite, they gain energy by affecting people. Any time they speak, they gain influence on the people that can hear them. No touch required to feed. Vampires are the number one cause of siren death, because they are also considered a delicacy. No high with this one, though.
Other supernatural creatures will be up to a vampire’s taste. Humans are their normal food supply, but some might go for it. Depending on who they are and how they view other supernatural creatures, they could see it as either eating better than human or eating worse.
Succubus and Incubus can feed off of anything, but they don’t eat people. They feed on electrical impulses that are created when people feel emotions. Lust is the most potent. They need to touch to feed, so they stay alive through touch. Not touching to feed will leave them weak.
Faeries eat sugar. That’s it, that’s all. They also gain energy and power from sunlight, moonlight, and contact with nature.
Banshees are humans with clairvoyant powers, basically. They can be born to anyone, so a normal human can birth a banshee and nobody finds out. Psychic mediums are banshees in this world. They have a vocal and precognitive power that they may or may not know how to use. Other than that, they are completely human so they eat human foods. They are very spiritual though, so they have spiritual weaknesses. Banshees can become immortal as well, if they become powerful enough.