Why did Shuri see the Ancestral Plane in "Black Panther: Wakanda Forever" [spoiler]?
"Only the most broken people make great leaders."

Editor's note: The following contains spoilers for Black Panther: Wakanda Forever.
^ The MCU has determined that there are other planes of existence that can be accessed from the Material Plane. These planes are not easily accessible, and unless you have magical abilities, the only way to get there is often a near-death experience. We've seen some of these planes in Doctor Strange, Avengers: Infinity War, Moon Knight, and especially the two Black Panther movies. In Wakanda, another dimension is the Ancestral Plane - the afterlife where Wakandans believe their souls go after death. Panthers can also visit the Ancestral Plane after consuming the Sacred Heart Grass. And that's exactly what Princess Shuri (Leetitia Wright) does in "Black Panther: Wakanda Forever," now available on DIsney+.
There was a lot of speculation about who the new Black Panther would be before the sequel was released. Possibilities include several female characters such as Shuri, Nakia (Lupita Nyong'o), Okoye (Danai Gurira), as well as Winston Duke's M'Baku and Daniel Kaluuya's W'Kabi. However, most manga fans expect Shuri to take over in her brother's absence, as this is one of the most prominent storylines in the manga. Shuri resists her fate Halfway through the movie, when she finally gives in, it's not a decision she makes lightly.
Shuri Is Our New Black Panther

After losing her mother, Queen Ramonda (Angela Bassett) and the attack of the incoming Namor (Tenoch Huerta Mejía), Shuri realizes that the only way she can protect her country is by becoming the Black Panther . But she must complete a ritual of ingesting the herb and be mentored by a former warrior before she can become a warrior.
We see T'Challa (Chadwick Boseman) undergo a similar ritual in the first film in order to communicate with his father, King T'Chaka (John Kani) in the Ancestral Plane. When Erik Killmonger (Michael B. Jordan) stole the throne and the Black Panther suit, he also met his father. But Shuri was not so lucky. Most viewers would guess that Shuri won't be able to meet the person she most wants to see - her brother T'Challa. The film's creators still respect Boseman's passing and did not include any enhanced footage of him. In T'Challa's absence, the warrior Shuri needs to mentor must be her mother, right? wrong! Guest appearances from writers Ryan Coogler and Joe Robert Cole are both fan-serving and vital to Shuri's heroes travel. Shuri appears in an ancestral plane that looks like the Wakanda throne room underwater after Namor's first attack. She turned to the throne to find Killmonger seated in her mother's place. Why did Shuri meet Killmonger instead of the one she loves? There are several reasons for this.
The Ancestral Plane

The heart-shaped herb that Shuri consumes was artificially bred in her laboratory, so the properties of the plant may not respond in the same way as the natural plant - perhaps it tends toward darker moods rather than calmer ones. But the heart-shaped herb is only part of the problem. When Shuri entered the ancestral plane, her state of mind was completely different from that of her brother in Black Panther. Also, she never cared about Wakanda's ancient traditions, so Shuri had to force herself to undergo one of these rituals, which went against her personal beliefs.
Why Killmonger?

Shuri doesn't interact much with Killmonger in Black Panther, but the two cousins are outraged by the loss of their family - Killmonger was orphaned after his father N'Jobu (Sterling K. Brown) was shot dead by young T' tea card, and Killmonger was subsequently abandoned. Likewise, Shuri is in disarray, still struggling to cope with the death of her brother, whom Shuri thinks she should be able to save with her scientific talents. In fact, her heart-shaped herb made from Talocan flowers could save T'Challa's life, but Shuri is unaware of its existence. Besides that, Shuri is now an orphan after her mother was murdered by Namor, just like Killmonger.
They are both fueled by the need for revenge. Killmonger has spent his life searching for his native Wakanda to take the throne and fulfill his father's mission of using Vibranium to end the oppression of the world's black people. Suri is saddled with her new role as ruler of Wakanda, which goes against her desire to kill Namor for her mother's assassination. The two characters also share a family bond because they are not accepted by Wakanda. Killmonger was an outsider who brought his own violent tendencies to his brief reign in Wakanda. Shuri believed in science and always rebelled against the traditions and rituals of her country, the leader of the Jabari tribe, M'Baku (Winston Duke) keeps reminding her.
Consumed by Vengeance

Cousins don't see eye to eye on the Ancestral Plane, but they are emotionally one - driven by searing grief and untamable vengeance. Ideologically, however, Shuri and Killmonger couldn't be more divided. Killmonger has murder as his greatest skill, while Shuri has always believed in the power of science. Then how did Su Rui meet her cousin in the ancestral plane? Because there's another guy in Black Panther: Wakanda Forever that evokes the same ideas as Killmonger.
Earlier in the film, Namor kidnaps Shuri and introduces her to his underwater world of Talocan. But he also hates the surface world as much as he does for oppressing people who look like him and Shuri. His intention was to declare war on the world, and the conquest of Wakanda would be a step towards a global war on Namor. If this sounds familiar, it's because Killmonger intends to do the same for his community. Namor's words were still fresh in her memory, and it was no coincidence that she met another nemesis of her own country on the ancestral plane. Granted, finding the Killmonger instead of her loved one must have felt like a cruel trick of fate for Shuri, But in a way, her ancestors have been taking care of her, because the best way to defeat your enemies is to know them.
The Ancestral Plane doesn't even look the same to Shuri and the Killer. T'Challa, who we can assume most of his ancestors, visited the ancestral plane with a clear purpose and sense of self, but Shuri and Killmonger are at odds about who they are and what their mission is, which would explain their divergent visions. As T'Challa enters the legendary green prairies filled with ex-Panthers, Killmonger sees his childhood home because that was the last time he was happy and he can never let go of his loss. Shuri is also still too grounded in reality and her pain, so her version of the plane reflects the world she briefly left.
A Different Ancestral Plane

Shuri eventually meets her mother on the plane, but this is the final scene of the film. Heart Grass was not among them, and it was after she was badly injured. Could it be a fever dream? What's more, what is the difference in the experience in the ancestral world? heart shaped herb seems to be sending Shuri, T'Challa, and Killmonger enter a near-death state, so it's possible that Wakanda saw their ancestors in a semi-comatose state. Shuri's trip to the ancestral plane also shows that the Wakanda ancestors were a tolerant people. They seem to have accepted Killmonger as one of their own despite the havoc he caused.
Finally, Shuri's interaction with Killmonger is more than just a much-anticipated cameo. Finding the killer dealer on the throne and hearing his violent perspective gives her the chance to face her emotions, no matter how dark they may be. But meeting Killmonger also gives us a glimpse of how her rage and desire for revenge will lead to destruction, not just for Namor, but for Wakanda as well. Her need to be reminded where the road leads (plus her mother's nudge) will help her make the right decision to save Namor's life and their country. As the MCU expands, we can expect to see more planes and realms, as well as characteristics of each realm.
Black Panther: Wakanda Forever is now available on DIsney+