A Nightmare or a ‘Mara’ is a dark fae that steals one’s breaths at night. They do the bidding of The Grimms and are created by them.
“When a soul is broken and dreams have turned to terror,
Mother Grimm will weave a dark fae – a Nightmare barer.
A Grimm little creature made of spite and some malice.
He just finished stealing the last breath from dear Alice.
As you lay down to rest it watches you drift,
silent in it’s plotting for not a stitch had been lift.
Beware standing on the abyss of sleep,
your future is grim when nightmares you keep.“
Nightmare fae are dangerous house creatures to keep, unless you name them in the proper way – they will not listen to you.