Thorax

Thorax is a male changeling and supporting character who appears briefly at the end of the season six episode The Crystalling - Part 2 before making his prominent debut in The Times They Are A Changeling. In the season six finale, he becomes the new leader of the changelings following the defeat of Queen Chrysalis.

Design and development
In contrast to other changelings such as Kevin, Thorax has somewhat wholer ears and tail, rounder and slightly differently-colored eyes, and differently-colored back armor. Following his transformation in To Where and Back Again - Part 2, Thorax is much taller, and he has a different color scheme and beetle-like mandibles.

In entomology, the term "thorax" refers to the midsection of an insect's body.

Depiction in the series
Prior to his introduction, Thorax appears briefly at a distance in the final shot of The Crystalling - Part 2, flying towards the Crystal Empire.

In The Times They Are A Changeling, Thorax appears pretending to be Spike's mirror reflection, but he is exposed when he does not copy Spike's exact movements. Spike is scared of Thorax at first, but he starts to warm up to him after Thorax saves him from falling into a deep crevice. Thorax explains that, unlike the other changelings, he wants to make friends, having desired so ever since he saw the Mane Six fight off the evil changelings during the royal wedding in Canterlot.

Thorax also explains that he was drawn to the Crystal Empire due to the love the Crystal Ponies had during Flurry Heart's Crystalling, but he has been unable to sustain himself off of that love because of what he is. Spike, sympathetic to Thorax's dilemma, decides to help him.

After Spike fails to convince the ponies of the idea that a changeling can be nice, he has Thorax disguise himself as a Crystal Pony—proportioned similarly to Plaid Stripes, "Pearly Whites", S06E24 Unnamed Pegasus Filly #1, filly Fluttershy, later filly Applejack, and later filly Derpy—named Crystal Hoof. With this disguise, Thorax is able to meet Princess Twilight Sparkle and mingle with the Empire populace. However, his cover is blown when he meets Flurry Heart and the love around her causes him to succumb to his basic instincts. In the confrontation that ensues, Spike briefly hesitates to stand up for Thorax, and Thorax runs off in tears, feeling betrayed.

When Spike returns to Thorax's cave and attempts to make amends, Thorax angrily turns him away at first, but he demonstrates his friendship by saving Spike from the crevice a second time. Spike brings Thorax before the ponies again and expresses through song that Thorax is good and that even changelings deserve a chance at friendship. Twilight, moved by Spike's courage and kindness, accepts Thorax as her friend, and the other ponies follow suit, welcoming Thorax as an official citizen of the Crystal Empire.

Thorax gratefully accepts the ponies' offer of friendship and expresses a desire to learn all he can about friendship and share what he learns with his fellow changelings so they can share love with each other instead of stealing it from others.

In To Where and Back Again - Part 1, Thorax teams up with Starlight Glimmer, Trixie, and Discord to save Equestria from changeling invasion. Here, his wings have become coated in crystal glitter. In Part 2, Thorax is forced to confront his doubts about returning to the kingdom where he was born, and he guides his allies into the Changeling Kingdom when the properties of Queen Chrysalis' throne disables their magic.

Near the end of the episode, it is revealed that Thorax's wings changed as a result of him sharing love with the Crystal Ponies. When Chrysalis tries to absorb that love from him, he follows Starlight's advice and shares it with her willingly, causing a blast of magic that metamorphoses him into a new colorful form. After Chrysalis is defeated and chased off, Thorax becomes the new leader of the changeling hive.

Personality
In The Times They Are A Changeling, unlike most of his kind, Thorax is demonstrably amiable and considerate with a sincere yearning for friendship. However, prior to meeting Spike, he bears much doubt that anyone could ever want to be friends with a changeling. When offered kindness or surrounded by love, Thorax occasionally reverts to his basic impulses and hisses threateningly at others.

In the two-part season six finale, Thorax is shown to panic when a situation turns dire, even to the point of hyperventilation. He looks to Starlight Glimmer for leadership, and he demonstrates selflessness such that he puts on her appearance to spare her the changeling queen's wrath until she can destroy the queen's throne.

Quotes
"The ice is pretty slippery. I wouldn't want you to get hurt because of me."

- The Times They Are A Changeling

"I'm Thorax. I can't believe you want to help me."

- The Times They Are A Changeling

"[hisses] Uh! S-Sorry! Kindness like that kind of brings it out. Do you still wanna be my friend?"

- The Times They Are A Changeling

"I like to brag to all my friends about my letters from Spike the Brave and Glorious."

- The Times They Are A Changeling

"I... [hisses] I'm so... [hisses] ...sorry...! I can't... Can't [hisses] ...stop!"

- The Times They Are A Changeling

"Why do you think I would help you? I'm an 'evil changeling'!"

- The Times They Are A Changeling

"I want to know all about friendship, and maybe one day I can take that knowledge back to the Changeling Kingdom! If my kind learned how to create love for one another, maybe they wouldn't have to take it from others!"

- The Times They Are A Changeling

"I'd hoped never to see that place again."

- To Where and Back Again - Part 1

"Nothing other than changeling magic works here. Chrysalis' throne is carved from an ancient dark stone that soaks up outside magic the same way changelings soak up love. It's how she keeps the hive safe."

- To Where and Back Again - Part 2

"It's a changeling hive. It shifts and changes like we do, and we're the only ones who can navigate it."

- To Where and Back Again - Part 2

"Once I made a few friends, I guess I just sort of forgot about the whole feeding thing."

- To Where and Back Again - Part 2