My Brother Is a Robeast is the seventeenth episode of the lion series of Voltron: Defender of the Universe.
King Zarkon and Prince Lotor grant an audience to King Coba of Planet Pollux in the throne room of Castle Doom. Prostrate before Zarkon, Coba explains his plan to take down planet Arus: have his son and heir, Prince Avok, become a Robeast and destroy Voltron. Skeptical, Zarkon demands that the prince prove his worth in the castle's arena. Avok goes to the arena, sword in hand, and in front of cheering crowds, easily takes down a Robeast in a so-gory-it-must-be-off-screen manner. Still in denial (and perhaps a little jealous) of Avok's ability, Lotor decides to go into the fray and duel with Avok, wielding his glowing energy-sword. A blond girl present there speaks about how strong her older brother is, and Lotor looks at the woman and notices she looks like Princess Allura.
Distracted by the pretty girl, Lotor is disarmed by the visiting prince. He swears to challenge Avok again. He walks up to the woman, and introduces himself. The woman introduces herself as Princess Romelle. Standing beside her is a red-haired pre-teen boy; he is Prince Bandor. Lotor's focus remains on Romelle, however, and he offers to show her around, beginning the tour with the statement, "You look just like Princess Allura!" (One can only assume that it grows still more awkward from that point on, if Lotor show's her Planet Doom's scenic route....) Meanwhile, an eager Haggar escorts Avok out of the arena to bring him to her laboratory and turn him into a Robeast. Amidst the crowd, Coba shows some hesitation in his decision to have Avok fight Voltron, in no small part motivated by him not being pleased at the sight of Lotor hitting on his only daughter.
Zarkon has a meeting with Haggar and Lotor. The plan is to kill Avok after he destroys Voltron, and as the aged King Coba will soon be gone as well, leave the little Prince Bandor in charge. Haggar says that Romelle means nothing, yet Lotor replies that Romelle means something to him. Zarkon orders Lotor to go to Planet Pollux, the world ruled by Coba's kingdom, assuring him that he can have Princess Romelle after they have destroyed Voltron. Lotor looks forward to owning both Princesses.
Landing on an airfield in Pollux's royal castle, Coba greets the Doomites. Lotor says that Haggar has already transformed Avok into a Robeast, and that as he was a willing subject to the process he was able to endure over "ten million units of laser-thermo rays" (which, as any nuclear physicist will tell you, is a lot). Coba is eager to divide Arus between him and Zarkon. Lotor orders Mogor to reveal Avok, and he does. Avok arises from the Space Coffin, a giant blue man.
Some time later, the Castle of Lions receives a message from Pollux stating that it is now allied with Planet Doom and thus quite capable of conquering the people of Arus, and demanding that they fight or surrender. Allura and Coran brief Keith and the others on the history of Pollux. The first king of Arus had two sons- one peaceful, one warlike. The warlike son was exiled to Pollux just before the first king died. The people of Pollux held a grudge against Arus to this day. Keith decides it is time to make peace, and Allura agrees. Despite the danger, the Princess insists on accompanying the men of the Voltron Force to fulfill her royal duty as ambassador.
The Voltron Force deploy the lions, form Voltron, and head to Pollux.
In the meantime, Coba meets with his staff. He reveals his ambitions to rule all of Arus and the universe, and to take down Zarkon. But Haggar's cat is scrying on the meeting, and Lotor and Haggar know of Coba's ambitions.
The Voltron Force, having disembarked Voltron, sneak through the main waterways underneath Pollux Castle. Looking through a window, they see Pollux's attack ships. Swimming to the surface, they look at the main keep. They use crampons stored in their belts to enter the keep via a window in one of the upper floors.
Inside a hallway, Romelle speaks with Bandor. Bandor has faith in Lotor, looking forward to having his own castle, but Romelle is skeptical of Lotor's intentions. She looks at Planet Arus, which is visible in the night sky. The Voltron Force just happen to be on that same floor, and Pidge backs into the sword point of a knight statue, which scares him. Assuring his comrades that his cry remained unheard, the young cadet backs into another sword point, and this time it is a sword held by Bandor. Pidge does his best to talk his way out of it, and the others arrive. They notice how much Allura looks like Romelle.
Allura asks that Arus and Pollux make peace, but Bandor is strongly opposed to the idea. Suddenly, Mogor and his soldiers arrive to capture the Voltron Force. A firefight ensues, and only one of the seven Doom soldiers is hit (yet Doom apparently sponsors Storm Trooper Academy, as none of our heroes are even nicked despite the shootout occurring in a straight hallway about 10' across). Lance somehow manages to survive diving into the moat from the upper floor.
The team re-enters Voltron (whom they had somehow managed to discreetly hide in a section of moat the size of a public swimming pool despite said Defender of the Universe being approximately 200' in height) and he arises from the castle moat. Voltron then breaks into the courtyard to destroy Pollux's fleet. Mogor orders Avok to battle, and Avok appears from the space coffin and is enlarged. "Voltron, prepare to meet your Doom!" the Prince cries, ready to do battle and make puns. Being all out of puns, he instead makes a dual-bladed sword.
Voltron forms the blazing sword, and Avok knocks the blazing sword out of his hands. Avok's own sword is knocked out in turn by the spinning laser blade, and the two engage in hand-to-hand combat. Avok throws down Voltron, and Keith reroutes the lion torch to fire out of his (Voltron's) mouth at the prince. The battle goes to the moat, and though Allura notes that Voltron's titanium shielding is caving, he temporarily keeps Avok at bay (no pun intended) with an argon force field. Out of patience, Lotor orders Mogor to fire upon both combatants. Avok is seriously wounded and swims out to sea off-screen, never to return. Romelle runs to look for Avok, and is captured by Doom soldiers. Bandor runs after her, and is shot in the leg. Now a captive of Doom, Romelle is taken on board a Doom ship. Voltron attacks the ship, and Lotor escapes with Haggar, Mogor, and Romelle on an interstellar shuttle before the ship explodes. He says he would have to land on Arus for fuel, his foot on Mogor's head.
On the surface, Bandor decides to make peace with Arus, and worries that he will never see his sister again. Allura mentions that Lotor will have to land on Arus and will probably have to trade Romelle for fuel. This causes the little prince to take heart and declare his gratitude that Pollux and Arus are friendly once again. Keith states that friendship is the greatest thing in the universe, echoing Allura's final thoughts at the end of a recent episode.
Coran (nodding): "That's exactly right." *standing* "I will go with the Voltron Force." (Because that worked so very well last time.)
Princess Allura: "No, Coran. It is my duty as Princess of Planet Arus to go and represent my world in peace!"
Princess Allura (gasping as though she had seen Witch Haggar's cat revealed in the immediately-preceding shot): "We mustn't fight! If there's to be peace, it must begin here!"
Prince Bandor: "Who said anything about peace? When the fighting starts even Voltron can't help ya!"
Princess Allura (tearing up): "Romelle, listen! Maybe between us we can bring peace!"
Pidge (looking out the window and spying ~80 armed soldiers): "Hey team, guess what? I think we're surrounded!"
Notes and Goofs
- In the first scene, King Zarkon's left hand is at one point shown as though it were behind his head, yet still in front of his ear.
- First appearance of Romelle, Bandor, and Mogor.
- Zarkon clearly had a tanker ship waiting for Lotor near Pollux. 
- Romelle later mentions having met King Alfor as a child, implying that he had tried to make peace with Pollux. While he made some impression on Romelle, he did not make a good impression with Coba. Of course, it is likely Coba had not been crowned king of Pollux yet.
- The castle the Voltron Force visited did not appear to be located in a city- unlike Castle Doom and the Castle of Lions. Was this a retreat away from the main palace in the royal capital?
- Coba was certainly very ambitious. He was hoping that the war between theGalaxy Alliance and the Drule Empire would exhaust both sides to the point that he could start taking over the galaxy. He never got to realize his ambitions.
- Pollux is apparently within sight distance of Arus, and was allied with at least Planet Doom, if not the Drule Empire, and yet neither Yurak nor Lotor ever mentioned using Pollux as a staging ground for attacks on Arus, even though Doom had attacked Arus at least fifteen times prior to this episode.
- Keith does indicate the rarity of Pollux's close proximity when he states how fortunate they are that it is the time when Arus' orbit brings it close to Pollux...once every hundred years.
- Nevertheless, despite Arus now being so close to Pollux that it appears larger than the Moon in the night sky (which must wreak havoc with its tides; maybe Avok really did go out to sea), Voltron is shown engaging his/its interstellar thrusters to travel to the latter planet.
- After Prince Bandor holds Princess Allura at sword point, Hunk body-checks him, causing the former's torso, right arm, and even his skirt to briefly turn a bruised colour.
- Prince Avok's robeast form is 230 ft. tall (tying for 4th-largest encountered thusfar with Dieklops and Beyel & Zebub), yet the heaviest robeast Voltron has encountered during the series at 4,500 short tons.
- Its somewhat strange that Avok's death was not confirmed when both Commander Yurak and the Clawbeast death's were not censored. This perhaps has to do with Avok turning back into a human before dying in Golion. Avok's death is kept in some foreign language dubs of Voltron.
- Prince Lotor, son of the intergalactic big bad, is going to land on a hostile enemy planet with a royal captive and barter her for fuel to return to the seat of his evil empire, all without being accosted and/or held for ransom.
- It seems diplomatic immunity is diplomatic immunity.