Happy-go-lucky and passionate about her job, Karenna spends the bulk of her time as a Priestess of Grenth. Despite her outwardly bubbly appearance, Karenna is quite comfortable with death and the dead, often making morbid comments that set others off-guard. She is confident, headstrong and fearless. This does not stop her, however, from delivering empathetic care to bereaved families of the deceased.

Karenna was born to a large common family with many sisters. When she was only a year and a half old, she fell deathly ill. Her parents, in desperation, took her to Grenth's temple and prayed that he spare her life. Their prayers were answered, but in exchange Karenna was to dedicate her life to the service of the God. They agreed. Karenna grew up happy to serve her God, and became a Priestess at the young age of 16.

She traveled to Maguuma to help care for the injured and perform rites for the dead when the Pact Fleet crashed, eventually teaming up with the Commander and company to take the fight to Mordremoth.

After the events of Heart of Thorns, Karenna becomes enamored with Archon Pydre's spectral magic, and, to his dismay, firmly requests that he teach her.  Over time, the two grow to love each other.

After mastering Spectral Magic to the best degree that she can, Pydre discovers that in the long term, the magic is fatal and has permanently damaging effects. Wanting to spare her from this fate, he insists that she stop practicing immediately. In order to help Pydre with his chronic spectral pain, she works with Talæesyn to learn healing magic and eventually develops a form of necromancy that relies on barriers and healing to support him in battle and beyond.