Fans claim that the only way the celestial mum can return to earth in "Lucifer" Season 5 after she was banished is if she uses the Flaming Sword Lucifer left in her new realm.

Lucifans have shared theories on who Tricia Helfer reprises in "Lucifer" Season 5 following news of her return to the series. She played both the lawyer, Charlotte Richards, and the Goddess, Lucifer and Amenadiel's mum, in Seasons 2 and 3.

Viewers believe that Helfer reprises mum and not Charlotte since the latter has gone up to heaven. As for mum, she is still alive in the new realm where Lucifer left her at the end of Season 2. Fans may remember that the devil did not bring her back to the Silver City or to Hell. Instead, he used the Flaming Sword and opened a new realm for her to rule over.

The Goddess stepped inside and without thinking, Lucifer threw in the sword after her. Now, fans are convinced that mum returns in "Lucifer" Season 5 and she will use the sword to return to earth.

"Technically, it's entirely possible that Goddess returns. We know it took the Flaming Sword to open up the way to a new universe, and Lucifer tossed the sword into the void before it closed, so she has it," a fan named h2p012 shared on Reddit.

The Flaming Sword, on the other hand, can only be used by the Lightbringer, which means only Lucifer can wield it and use its full potential. The fan shared a possible solution on how mum can use the sword to her advantage in "Lucifer" Season 5.

Light bringer, bringin’ light😈 #Lucifer #LuciferSeason5 #bts #latergram

— Aiyana White (@AiyanaEWhite) November 25, 2019

"Yes, Lucifer was the only one who could use it, but when Goddess regains at full strength, she could theoretically change that requirement with the sword. After all, the only backstory of the sword was that it guarded Eden, God broke it after the rebellion, and Lucifer was the only one who could use it," the fan explained.

It is not known who Helfer will portray in "Lucifer" Season 5. But the promotional photo used to announce her return suggests she plays neither mum nor Charlotte.

Interestingly, an episode in "Lucifer" Season 5 teases at the return of the Goddess. Perhaps mum, Amenadiel, God, and Lucifer all sit down together as one happy family in Episode 9, titled "Family Dinner."

Tricia Helfer and Tom Ellis to return in "Lucifer" Season 5. Lucifer/Fox