Thorax

King Thorax is a Changeling and current leader of the Changeling kingdom and good personal friend of, , and Starlight Glimmer.

Befriending Ponies
Unlike the Changelings with whom he was hatched and raised, Thorax saw no appeal in the vicious and violent ways of, and went along with her rule only because he saw no alternative. He was defended in his youth by his brother Pharynx, though the other Changeling understood his brother's gentle ways as little as the rest of their kind and teased him in his own turn. He took part in the Changeling invasion of Canterlot, and during the conflict witnessed the friendship of the Mane Six. This inspired him, and when the Changelings were repulsed from Canterlot, Thorax struck out on his own, eventually making his way to the Crystal Empire after the Crystalling of Flurry Heart.

Thorax sought to befriend the Crystal Ponies, but knew that they feared him and was thus unsure of how to approach them; when his presence became known, the Empire went on high alert. However, after met him and heard his story, he became determined to assist Thorax in his efforts. Taking the form of a a Crystal Pony whom Spike dubbed "Crystal Hoof", he joined Spike in traveling around the Empire and befriending the inhabitants. Unfortunately, when he was brought to the Crystal Castle throne room and introduced to the royal family, the love coming off of Flurry Heart caused him to revert to his normal form. The Crystal Ponies quickly assumed that Thorax has kidnapped and impersonated the "real" Crystal Hoof, and Spike failed to stand up for his friend, who was forced to flee.

Spike eventually tracked down the angry Thorax, who later saved Spike from a dangerous fall despite feeling betrayed by his friend. Spike then brought Thorax back to the palace, and explained the truth about who he was and their friendship, which moved to speak up on his behalf as well. Their words together helped persuade the Crystal Ponies, who soon welcomed Thorax; grateful, he expressed the hope that he could learn about love and take his knowledge back to his people. Thorax's hunger for the love of others dissipated, and his wings took on a crystalline sheen as he learned the value of friendship.

Return to the Changelings
Thorax would be forced to return to his people much sooner than expected, however, when Chrysalis enacted a plan that led to the capture and replacement of the Mane Six, Spike,, , , , and Flurry Heart. Sunburst, Flurry Heart's Crystaller, sent Thorax to Ponyville for help, but he arrived after Twilight and her friends had already been captured. He did encounter Starlight Glimmer and, and after proving his identity to them informed them of the capture of the Crystal Empire royals. The three then met, who quickly transported them to the Changeling Kingdom after learning of 's abduction.

Thorax was soon forced to explain that Chrysalis' throne negated all non-Changeling magic, as Discord's fruitless attempts to invade the kingdom's boundaries soon proved. The four unlikely allies were forced to make their way in on foot, and Thorax proved invaluable in helping navigate the ever-changing hive. Along the way, Thorax told his new friends about the changes he had felt in himself, but was then forced to pose as Trixie to distract a squad of guards. Discord was eventually separated from the others while providing a distraction, and replaced with a Changeling whom they were able to detect. Trixie then allowed herself to be captured to allow Thorax and Starlight to go on, with Thorax taking Starlight's form before entering the throne room.

Chrysalis appeared, and Thorax was restrained, with Chrysalis vowing to repay the errant Changeling and later forcing him to return to his normal form. However, when she attempted to drain his newfound love from him, Starlight encouraged him to share it with Chrysalis rather than trying to keep it from her. As a result, Thorax was transformed into a new, larger form, and the majority of the other Changelings soon followed his lead. The release of energy freed Chrysalis' captives and destroyed her throne, and Chrysalis fled after rejecting Starlight's offer to join her people in their new way of life. Thorax was thus named the new leader of the Changelings, and attended a ceremony at the Castle of Friendship honoring his heroism, though Luna had trouble getting his medal on due to his new horns.

Leader of the pack
Though many of the Changelings had accepted Thorax, several of them continued to cling to the old ways, and Thorax struggled to bring them around. He was thus thrilled when Spike invited him to visit Ponyville, hoping that his Dragon friend could give him some helpful advice. Unfortunately, Spike had accidentally invited Thorax to visit the same day he had invited Dragon Lord Ember, and Spike feared that the two rulers would clash and spark a Changeling-Dragon war. As such, he and his pony friends kept trying to keep the pair occupied and away from each other, inadvertently upsetting both in the process. When an angry Ember expressed her frustration with Spike, Thorax believed she was attacking him and transformed into a bear to confront her, only for the truth to come out as Spike panicked over the encounter.

Thorax and Ember both left in disgust, only to run into each other at a nearby lake, where Thorax opened up about his problems to Ember. She encouraged him to own his authority as the Changeling leader, and Thorax then helped her realize that she could be sensitive to the feelings of other and express her own without it being awkward. The two then returned to address Spike, whom they forgave after expressing their displeasure with his actions; both were then honored at a welcome ceremony initially intended for Ember alone. With Ember's help-which he continued to receive through correspondence with her-Thorax soon had all the renegade Changelings convinced but one: his brother Pharynx.

Starlight and Trixie soon arrived at the hive for a surprise visit, and became acquainted with the situation with Pharynx after he took them prisoner and brought them before Thorax. While he eagerly shared the changes in the hive with his friends, Pharynx caused continual problems with his behavior. The other Changelings, Starlight, and Trixie soon felt that it might be best to exile Pharynx, but Thorax refused to give up on the brother who had defended him in their youth. He was soon forced to deal with Starlight's efforts to help Pharynx by joining his brother in dealing with a Maulwurf that had been plaguing the hive recently. After the rest of the hive joined in and expressed their regret at wanting him to leave, Pharynx was able to embrace his own love for the hive, and transformed to join his people.

International relations
Thorax later joined a delegation of Changelings in attending the Convocation of the Creatures, a gathering of various creatures from around the world. Despite being regarded with some suspicion by other delegates like King Aspen of the Kingdom of Thicket, he and his fellow Changelings got along well with their peers. Some time later, Thorax and his people came to the aid of Daring Do and Brumby Cloverpatch after they crash-landed in Changeling territory aboard their airship, the Reflector. Thorax's party soon had the airship repaired, and asked the Ponies to spread the word of the Changelings' newfound good nature.

When Twilight decided to open the School of Friendship, Thorax arrived at the opening, bringing the young Changeling Ocellus to enroll at the school. He later attended Family and Friends Day with several other non-Pony representatives, including Ember, only for their students to cause a panic while ditching class. Chancellor Neighsay of the EEA condemned Twilight's allowing students to enroll, and Thorax and the other offended leaders soon departed for home with their young charges. When Twilight decided to reopen the school under her own rules, Fluttershy traveled to the Changeling Kingdom to ask Thorax if he would allow Ocellus to return. However, Thorax soon informed her that Ocellus had disappeared, and gathered in Canterlot with the other leaders when it was learned that their students had also departed.

Thorax attempted to urge calm among his angry fellow representatives, but Ember, Prince Rutherford, General Seaspray, and Grampa Gruff were all determined to go to war were their students not returned. Thorax worried about how his people might be affected, only to be accused of hiding the students by Ember despite their friendship. Fortunately, the Mane Six located the missing students, and Twilight and Celestia were able to prevent Thorax and the others from becoming violent when Neighsay again condemned their non-Pony status. Satisfied that Ocellus wanted to return to school and that she would represent the Changelings well, Thorax departed with his counterparts. Some time later, Thorax led his people in celebrating Hearth's Warming; later, he went looking for Ocellus after she responded to a summons from the Tree of Harmony.