Cake
She was briefly mentioned in "King Worm" when the Ice King was in trouble and mistakenly used the gender-swapped names when asking Finn and Jake for help.
from adventuretime.wika.com
Princess Bubblegum (full name Princess Bonnibel Bubblegum,[1] often called PB and on occasion Peebles, P-Bubs, or other nicknames) is a main character on the series Adventure Time that first appeared in the Animated Short. She is the benevolent ruler of the Candy Kingdom, and is Finn's former love interest. She is also Ice King's most often-targeted princess. Marceline is the only person known to call her by her first name, Bonnibel, or Bonnie for short. At the end of "Mortal Recoil," she was transformed into a 13-year-old, but returned to her normal biological age of 18 years at the end of "Too Young." She has a gender-swapped character named Prince Gumball created by the Ice King in a fan-fiction.
Flame Princess has a volatile personality; she usually has a calm
demeanor, though with rather frequent tendencies to sudden and violent
mood swings. She is described as "passionate" by Finn, "evil" by the
Flame King, and "intense" by Pendleton Ward.[1]
The Flame King also remarks that she is difficult to control. She seems
to be very sensitive and quick to judge. She is also prone to
unprovoked fits of aggression, as shown when she throws fireballs at her
citizens just for whispering. Flame Princess is also impressionable in a
positive way. She is very happy when Finn calls her beautiful. She was
also interested when Jake was giving her gifts in the episode "Incendium"
and excited when her dad let her date "Prince Finn," though this
excitement quickly turns to anger when "Prince Finn" rejects her.