Bubblegum is a Pokemon of the Fae realm who joined the traveling circus as a fortune teller while it was under the previous Ringleader. For some reason among his possessions there was a magical cabinet which contained a portal to the Fae realm.

Despite being a Fae with a silly name, Bubblegum doesn't seem as jovial and free spirited as most other fae pokemon, though sometimes if pushed some of that typical fae spirit comes through.
Most of the time she seems stoic and reserved, perhaps living in the mortal world so long has made her this way. The Fae realm is the Realm of Life, so Fae are not used to experiencing things like Death. Due to her job as a Fortune Teller in the Mortal she has had to visit the concept of Death and Loss more times than she would like, and it has been an ordeal for her to comprehend the idea of somebody being gone and unable to come back.
Now even the Ringleader she was friends with has passed away, and she didn't foresee it coming ahead of time, so she feels partially responsible, but she needs to protect the Ringleader's Daughter, The Circus Princess.