Rukiya was the female Human daughter of Doctor Joseph M'Benga and Debra.
She had a progressing case of cygnokemia, so she was kept in the transporter buffer of the USS Enterprise so she could stay in stasis. Sometimes, M'Benga brought her out to read her a book. One favorite was The Kingdom of Elysian by Benny Russell. (SNW: "Ghosts of Illyria", "Lift Us Where Suffering Cannot Reach", "The Elysian Kingdom")
As the Enterprise was surveying the Jonisian Nebula, M'Benga found himself and the rest of the crew in a surrealistic recreation of The Kingdom of Elysian, which was lifted from Rukiya's mind by the sentient non-corporeal lifeform speculated to be a Boltzmann brain, later named Debra by Rukiya. Seeing Rukiya inside the transporter buffer, Debra assumed Rukiya was imprisoned, and they shared a bond of loneliness. While Debra was in contact with Rukiya, her cygnokemia was cured, but it wasn't permanent.
Rukiya and M'Benga decided she would be better off staying with Debra as pure consciousness rather than risk time running out while M'Benga searched for a cure. Once with Debra, Rukiya experienced time rapidly and appeared to her father as an adult before the Enterprise left the nebula. (SNW: "The Elysian Kingdom")
Background information[]
Rukiya was portrayed by Sage Arrindell as a child, and Makambe Simamba as an adult in "The Elysian Kingdom".
Rukiya description
In the comic Star Trek, Issue 21, Rukiya M'Benga is shown to have gone on to live in the Pleroma, "a place outside time and space where god-level species have gathered to discuss the fate of the universe."