The protagonist was a female with a butterfly tattoo that travelled between realms, can’t remember if it was the fairy realm or Death’s realm.
She may have a romance with a guy that transforms into a coyote or fox (that might be from a different book, I’m not sure).
She either fought ghosts/creatures, or she helped them move on or something. I do remember that she was known by another name in the other realm.
Perhaps Storm Born, the first book in the Dark Swan Series, by Richelle Mead:
The Goodreads summary of the book is:
Just typical. No love life to speak of for months, then all at once, every horny creature in the Otherworld wants to get in your pants...
Eugenie Markham is a powerful shaman who does a brisk trade banishing spirits and fey who cross into the mortal world. Mercenary, yes, but a girl's got to eat. Her most recent case, however, is enough to ruin her appetite. Hired to find a teenager who has been taken to the Otherworld, Eugenie comes face to face with a startling prophecy—one that uncovers dark secrets about her past and claims that Eugenie's first-born will threaten the future of the world as she knows it.
Now Eugenie is a hot target for every ambitious demon and Otherworldy ne'er-do-well, and the ones who don't want to knock her up want her dead. Eugenie handles a Glock as smoothly as she wields a wand, but she needs some formidable allies for a job like this. She finds them in Dorian, a seductive fairy king with a taste for bondage, and Kiyo, a gorgeous shape-shifter who redefines animal attraction. But with enemies growing bolder and time running out, Eugenie realizes that the greatest danger is yet to come, and it lies in the dark powers that are stirring to life within her...
Below is the front cover:
The covers for the other three books in the series are below in case you recognise them too:
