The All Expanse
In this world, there exist three different realms. That of the Mortals (also known as that of the Humans), of the Channels, and of the Demons. Between each realm, there is a Rift. These Rifts can only be used by Channels (special animals with unique abilities). Other transportation between realms would require: a) magical spells and abilities or b) potent potions (which have some really bad drawbacks since little to no knowledge is known to the race who uses these).
This world has a number of conflicts and a great history behind it. The only race that is peaceful in every way is that of the Channels. Demons are war-driven and Humans... well... they're pretty oblivious to all of this if I'm being honest. There are only few who truly believe the existence of Channels and Demons, but there are still those who are aware of the magic within their realm and understand how there are others outside of their realm.
With that being said, Demons and Channels have a very adept awareness of magic. Channels have the ability to use one of their senses to locate magic (so if a bat happens to be a Channel, it obviously won't use sight, it'll use hearing instead to identify magic.) Demons on the other hand have a sixth sense which allows them to sense the presence of magic and identify magical beings.
Channels and Demons have a special relationship where Channels can use their special ability (different with each Channel) to act a certain way with Demons. This can be through the ability to put a being on edge, therefore, when the Demon is in the presence of that specific Channel, they will be put on edge (this feeling is usually amplified the closer a person gets to the Channel). Humans don't feel any of this as they have no senses regarding magic.