One Shall Fall is the eighteenth episode of the first season of Transformers: Prime. It is the twenty-third episode of the series overall.
After Megatron attacks Rafael and Bumblebee, leaving Rafael unconscious and severely injured, Optimus realizes that he can't end the Autobot-Decepticon conflict diplomatically, and decides to confront Megatron head on and destroy him once and for all,but fails
Optimus Prime recites a passage from the Covenant of Primus, foretelling that a perpetual conflict will culminate when the forty-seven spheres align. Despite the other Autobots' lack of faith, Ratchet realizes that the "world forged of chaos" referred to in the prophecy is Earth—and that the alignment will occur in a matter of days.
Aboard the Nemesis, Megatron explains to Knock Out that he sought the blood of Unicron so that he could conquer worlds with undead armies. Knock Out assures him that more Dark Energon awaits amongst the stars, but advises him not to push himself, since he was in stasis. Megatron then claims that he is the "rising darkness" of which the prophecy speaks.
Jack, Raf, and Miko find a picture of Bumblebee while searching a conspiracy website. Raf replaces the image with a dancing cat, which makes Ratchet laugh. Jack then invites Optimus to take a look, but is flatly denied. Ratchet then states that, before he became a Prime, Optimus behaved quite similarly to Jack. Agent Fowler suddenly interrupts and reveals that the Decepticons have been stealing components to build a second space bridge. Back aboard the Nemesis, Knock Out and Soundwave inform Megatron that the only item left on the list is an ample power source, which can be found in a heavily fortified human base. Airachnid could simply tunnel in, but Megatron rather angrily declares that the time for stealth is over, and he sends a massive squad of Vehicons to retrieve it. Optimus warns Fowler to have his troops evacuate, for fear of human casualties.
Optimus, Bulkhead, and Arcee arrive to fend off the Vehicons, and all goes well until Megatron himself heads out toward the battlefield. En route, he spots Bumblebee, who was taking Raf racing. Megatron opens fire, frying Bumblebee's systems and knocking Raf out cold. Megatron arrives at the base just as the Autobots disable the last of his drones, and he taunts Optimus as Bumblebee arrives whilst carrying a wounded Raf. Bulkhead restrains the enraged scout before Optimus orders Arcee to take him and Raf back to base. Megatron then ascends onto the Nemesis with the power source. Unbeknownst to Megatron, Optimus and Bulkhead climb aboard the Nemesiss hull.
Back at Autobot Outpost Omega One, Ratchet panics that his tools are wrong for human examination, and Jack suggests that they call in his mother. Meanwhile, Megatron has another vision in which he sees a sinister face and a volcano. He then orders Knock Out and Airachnid to complete the space bridge, as there is something he must attend to. June arrives at the Autobot base and quickly unnerves Ratchet with the knowledge that Raf will die unless she can stabilize him immediately. Bumblebee vents his frustration on a nearby wall, but Arcee manages to calm him...a little. Ratchet regrets having not bothered to learn human science and medicine, despite accepting the children into their lives. He then states that he has grown to need Rafael, just as Raf needs him.
Bulkhead and Optimus storm the Nemesis, and Optimus claims to have had a change of heart: He orders Bulkhead back to base with the power source, declaring that there is something he must do. He then muses grimly that he has realized that Autobots and Decepticons will never co-exist peacefully, and he vows to destroy Megatron.
As the planetary alignment nears, Megatron arrives at the volcano site, and Optimus uses a Vehicon comm link to challenge him. Optimus soon joins him at the base of the volcano, and the two exchange brief banter before engaging each other in fierce battle.
Meanwhile, Ratchet realizes that Raf has been infected with Dark Energon and theorizes that exposure to normal energon should cure him. He takes a sample from Bumblebee, placing Raf in a sealed chamber to test his theory as the others watch helplessly. Rafael soon opens his eyes, his pulse stabilizing.
Optimus appears to defeat Megatron and prepares to deal the final blow, but the Decepticon leader catches his sword with unusual strength as the volcano begins to erupt. Back at the base, Arcee scolds Bulkhead for leaving Optimus alone to face Megatron, which he revealed he didn't have a choice and Ratchet begins to detect for Optimus' location. Strange purple markings glow to life across Megatron's body, and he quickly overpowers Optimus. Ratchet's computer detects something and he warns the Autobots that they must get Optimus out of that area. As Optimus lays in the ground under Megatron's foot, Megatron realizes that the volcano is spewing forth Dark Energon, and he moves in to kill Optimus, as he saw himself doing in a previous vision.
- Peter Cullen as Optimus Prime
- Frank Welker as Megatron
- Sumalee Montano as Arcee
- Kevin Michael Richardson as Bulkhead/Trooper
- Jeffrey Combs as Ratchet
- Daran Norris as Knock Out
- Gina Torres as Airachnid
- Josh Keaton as Jackson Darby/Soldier
- Tania Gunadi as Miko Nakadai
- Andy Pessoa as Rafael Esquivel
- Ernie Hudson as William Fowler
- Markie Post as June Darby
Optimus Prime: And it was written in the Covenant of Primus that 'when the 47 spheres align, a perpetual conflict will culminate upon a world forged from chaos. And the weak shall perish in the shadow of a rising darkness.
— Optimus Prime reciting a passage.
Miko: Mars Cat says, 'Take me to your feeder!
— Miko starts a new internet meme.
Jack: Um, Optimus! You wanna see something funny?
— Jack learns of Optimus Prime's minimal sense of humor.
Knock Out: Does he seem to be...'losing it'?
Airachnid: A bit...
— Knock Out and Airachnid discuss Megatron's state of mind.
Optimus Prime: I have been foolish not to see what history has proven over and over again...that Autobots and Decepticons will never mend their ways. If there can be no diplomatic solution to this perpetual conflict, then I must not allow more darkness to fall upon this or any planet. Megatron must be destroyed!
— Optimus Prime vowing to terminate Megatron.
Optimus: Megatron! Today you answer for your crimes against Cybertron and against humanity. One shall stand...
Megatron: And one shall fall. YOU! Optimus Prime!!!
— Optimus and Megatron before their fight.
Megatron: Your defeat was foreseen here by the ancients. What was it they wrote? 'The weak shall perish'?
Optimus Prime: Do not believe everything you read.
— Megatron and Optimus Prime during their battle.
- Ratchet claims that Cybertron has been dark for eons, which is roughly equal to a few billion years, while other characters have claimed that Cybertron has been dark for thousands of years.
- When the flying Vehicons arrive to help retrieve the power source from the military base, the Vehicon ground units which stole it in the first place suddenly vanished.
- When Megatron arrives at the volcano, the points of his helmet disappear through his neck armor.
- As Megatron extends his blade when Optimus leaps at him, the sound effect is that of his cannon firing.
- When Optimus tries to strike the finishing blow, he's standing on Megatron's chest. Once Megatron catches the blade, Optimus is standing much further back.
- Megatron's jet mode cannons score a direct hit on Bumblebee, yet do no apparent damage other than briefly stopping him. When Arcee was hit in "Darkness Rising, Part 5", it nearly killed her. On a similar note, Bumblebee should have taken the brunt of the Dark Energon exposure, but only Raf shows any symptoms. Remember that Arcee was weakened by exposure to a few drops from Cliffjumper's animated corpse in "Darkness Rising, Part 2".
- However, Optimus tells Arcee to look after Raf and Bumblebee; it's likely that Bee's just being strong for his partner's sake. Bumblebee also handled a shard of Dark Energon during "Out of His Head" without any ill effects, so maybe he's just resistant to the stuff.
- Bumblebee knows Raf is injured, so why does he drive nearly two miles (three klicks) to the battlefield instead of just calling for a Ground Bridge immediately?
- Raf says he can't see without his glasses in "Shadowzone", but his first person shot is perfectly clear.
- Megatron refers to his feeling by saying "it's as if" he can hear Unicron's thoughts, which he gibbered about back in "Darkness Rising, Part 3".
- The story revolves around the idea that Dark Energon is out in space, another "Darkness Rising" plot point. Turns out that it's not as far out as the characters think.
- Agent Fowler's men at first thought it was MECH who stole the phase conductor until they found the security image of Soundwave.
- Starscream demonstrated that energon does not agree with human physiology in "Darkness Rising, Part 3" and "Part 4", which Ratchet confirms here. Apparently, Dark Energon has similar effects, but the two types cancel each other out (at least in a human).
- Arcee tells Bumblebee that she knows what it's like to see a partner killed/harmed, referring to Tailgate's death at Airachnid's claws in "Predatory". Her general speech seems to call back to the lesson she learned at the end of "Partners". Ironically, Bumblebee was the one who prevented Arcee from giving into her desire for vengeance in that episode.
- Ratchet extracts energon from Bumblebee with the same device that he used to inject himself with synthetic energon in the previous episode.
- The Covenant of Primus first appeared in the Beast Wars episode "Nemesis Part 1".
- Megatron and Optimus punch each other in the style of the opening credits, only on opposite sides. This isn't the first time the show has done this.
- "One shall stand, one shall fall." This is the third time in this series alone, following "Darkness Rising, Part 5" and "Sick Mind", and that's not even including the title of this episode. Megatron even completes the saying for Optimus, he's heard it plenty of times by now.
- Ratchet mentions that he has known Optimus for longer than any of the other Earth-stationed Autobots, even before he was a Prime. Taking the character's appearance in War for Cybertron into account, this would be true, as Ratchet was under the direct command of Optimus prior to, and at the start of the game's storyline.
- In comparison, the first cutscene of the Autobot campaign showed Bumblebee's first meeting with Optimus, and whilst Arcee was in the game, she never personally interacted with Optimus during the story. Bulkhead was mentioned as having joined Optimus during a later period of time.
- Megatron refers to Optimus as "the last of the Primes". He was also called this by the head of the High Council in War for Cybertron, upon his ascension to the rank of Prime. It is also a term used to refer to his live-action film counterpart.
- Megatron breaks Prime's sword just as in "Darkness Rising, Part 5."
- The episode was first broadcast on Canada's Teletoon channel. It later first aired in the United States on September 24, 2011
- This is one of the few episodes storyboarded by the artist Adam Van Wyk.
- At the beginning of the episode, as Megatron explains why he sought out the blood of Unicron, Knock Out totally checks out his "nails" in the background.
- Megatron laments that the only shard of Dark Energon he has is the one in his chest. It would seem that, despite his machinations being discovered, Starscream never gave Megatron's original shard back.
- Bulkhead states that he has never seen Optimus "laugh, cry or lose his cool". While it could just be an offhand expression, this inadvertently raises an interesting question as to whether Cybertronians actually have the ability to cry.
- Ratchet actually laughs in this episode, and at a cartoon space cat, of all things!
- When Jack dials his mother, it is evident he has her on speed dial from the sound of him pushing one button on his mobile phone and the phone dialing itself.
- The title is a reference to the famous quote "One shall stand, one shall fall" said in The Transformers: The Movie in the 80's by Optimus Prime. It has been repeated beyond reckoning ever since due to its fame.
- This is the second time Optimus and Megatron battle.
Main Article: One Shall Fall/Gallery
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