It can be argued, then, that upon Ben Solo's death, his life was absorbed by Rey and will live within her until her death, essentially uniting the two halves of the Force dyad in a single being. As such, Ben will only appear as a Force ghost when Rey also dies and appears as one.
Somehow, Obi-Wan or Yoda taught him how to become a Force ghost in time for Luke to see him in Return of the Jedi. Another theory stated that Kylo couldn't become his own Force ghost because he and Rey were part of a Force Dyad, meaning that his consciousness was absorbed into Rey when he died.
Force Ghosts have become part of the Star Wars franchise's lore, expanded upon in movies, numerous canon tie-ins, and even the Obi-Wan Kenobi Disney+ TV show. Some of the greatest Jedi returned as Force Ghosts: Qui-Gon Jinn, Yoda, Anakin Skywalker, Luke Skywalker, and Leia Organa.
It seems that with his last ounce of strength, Ben gave what was remaining of his life energy to save Rey. This was his last sacrifice, effectively acting as redemption to return him to the light side of the Force. That is why his body vanished, as Jedi like Luke Skywalker and Obi-Wan Kenobi and Leia did before him.
Summary. The ending of The Rise of Skywalker sees Leia as a Force ghost, but it's never explained how she was trained to do this after her death. Leia's ability to become a Force ghost isn't far-fetched, as she had three Jedi Masters who could have taught her - Luke, Obi-Wan, and Yoda.
Why Anakin's Force Ghost DID NOT appear in The Rise of Skywalker? - Star Wars Theory
Did any Sith become Force ghosts?
Also, the Sith Lord Ajunta Pall lived on through the Force in such a manner as a Force ghost, though it is relatively unknown how or why he remained. However, it can be speculated that his extreme rage and anger made his presence linger.
Why didn't Mace Windu showup as a force ghost? Qui Gon died before he could finish his training so he can only appear as a voice and not a physical form. Mace Windu never studied or trained in that aspect of the force.
But this is actually a very sad reason because it actually had the opposite effect, and he deeply regretted his decision to kill his father and it haunted him for the rest of the trilogy. Also, Han was telling him that Snoke was using him, but one of the reasons he killed him was to impress Snoke.
The Rise of Skywalker novelization insisted the kiss was not romantic, explaining that it was “a kiss of gratitude, acknowledgment of their connection, celebration that they'd found each other at last”, but when looking at the context and what their connection was like since The Last Jedi, the kiss between Rey and Ben ...
Anakin's spirit did return to help Ahsoka overcome her past trauma and to make amends with his former Padawan for the terrible things he did as Darth Vader. The last shot of Ahsoka season 1 presents the scene from his perspective, removing all doubt that he was only in Ahsoka's head.
The closest that Star Wars canon has come to naming who trained Yoda was revealing that Jedi Master Qui-Gon Ginn was the one who taught Yoda to become a Force Ghost and attain immortality.
In material that is now considered Legends, Qui-Gon is even described as a Gray Jedi. Additionally, the term has also been applied to Force-sensitives who aren't affiliated with the Light or Dark side of the Force. Quite literally, these Gray Jedi don't see things in black and white, or light versus dark.
However, joining the Sith means declaring loyalty to the dark side, which Anakin did before his eyes turned yellow. This may explain why Kylo Ren, torn between the light and dark, didn't have yellow eyes in the Star Wars sequel trilogy, as killing his father split his spirit even more.
It's assumed that Qui-Gon began these trials long ago, but was not able to complete them before being killed by Darth Maul. That, in turn, explains why he never appeared during the prequels or anything after. Yet with the ending of Obi-Wan Kenobi, Qui-Gon has seemingly found a way to appear as a Force-ghost.
According to official tie-ins, Anakin's Force Ghost would visit Luke many times over the next decade, offering him guidance and counsel as he reestablished the Jedi Order. Lucasfilm has published an excerpt from Adam Christopher's upcoming novel Shadow of the Sith, revealing Anakin was far more than just an adviser.
Affiliation(s) Zayne Skywalker, a Human male Force-sensitive, was the son of Ben Solo and Rey Palpatine, a dyad in the force as the great grandson of the Chosen One and the son of powerful force wielders, who later becomes a legendary warrior and hero for the galaxy in the decades after the Battle of Exegol.
Following Palpatine's final defeat and her own resurrection, Rey adopts the name Rey Skywalker to honor her mentors and their family legacy and renounce her lineage. As the last remaining Jedi, she makes it her mission to rebuild the Jedi Order.
Rey and Ben kissing. Ben Solo is the love of Rey's life. Initially unknown to Rey, she forms a dyad in the Force with Ben. The dyad is an unbreakable Force-bond that makes them one in the Force, despite being born as two physically separated individuals.
Why does Kylo Ren punch his blaster wound during his lightsaber duel with Finn? To generate pain and thus adrenaline. The Dark Side of the Force feeds off of such things; anger, pain, fear. Earlier in the movie we'd seen Chewie blast some poor Stormtrooper and send him flying despite his armor.
Kylo Ren dies on Kef Bir (the ocean moon of Endor) shortly after Rey deals a mortal wound during a lightsaber duel on the wreckage of the second Death Star. Though Rey Force-heals him, saving his life physically, this blow, coupled with the memory of his mother and father, destroys the man known as “Kylo Ren” forever.
After Kylo's confrontation with Rey in The Rise of Skywalker, he's left to ponder all his decisions and regrets while surrounded by the ruins of the Death Star. Harrison Ford then makes his surprise return as Han Solo, who forgives his son and provides Ben Solo the closure he needs to leave Kylo Ren behind.
Katri was a Mirialan Jedi Master and member of the Jedi Order's Jedi High Council. Between 68 BBY and 42 BBY, she was killed by a group of security guards on Raxus Secundus, and her death was investigated by Jedi Masters Mace Windu and Dooku. Her seat on the Jedi Council was awarded to Windu.
Legend had it that Yoda—a Jedi who became Grand Master—was trained by N'Kata Del Gormo. A Force-sensitive Hysalrian, N'Kata Del Gormo was trained in the ways of the Force and achieved the rank of Master within the Jedi Order.
