I think it is a coincidence that both Kamen Rider Dragon Knight and Power Rangers RPM have dark themes and are so serious. I think Children's programming with serious themes are great, because kids get more than we believe. Growing up, I loved shows like X-Men (1993), Roughnecks: Starship Troopers (1997), Jem (1984)--rehab for an injury anyone?, etc. Anyhoo, tough times and war time does translate into film/television/etc. Art imitating life. Power Rangers RPM gives us a post-apocalyptic world, which is not the first time it has happened.
Sonic the Hedgehog (known as SonicSatAM to fans) in 1993 dealt with rebels against the ruler of the world--Robotnik , Spider-Man Unlimited (1999) dealt with a world taken over by evil, Beast Machines (1999) with the same theme and She-Ra also dealt with rebels against evil hierarchy, but not exactly an Apocalypse but it was the end of peace. Kamen Rider Dragon Knight gives us some real world themes like a marine eager to save his country towards a threat, imprisonment, comas, etc. The one most apparent thing both series have in common is humans held prisoner and used for slave labor. One of the differences is that Dragon Knight is rather close to its original counterpart Ryuki, while RPM goes far from its counterpart Go-Onger.
Power Rangers RPM
A new computer virus known as the Venjix Virus had infected all the computer systems and had taken over the world's communication, power and defense systems. It was created and sent out by a teenage phenom forced to work practically her whole life, so to make up for it, she helps fight against Venjix with her own Power Rangers. Her only friends ever were twin prototype testers she believed where dead and after that, she swore not to get close to anyone else again and didn't call the Rangers by their real names. The dome city of Corinth was created as a safe haven by the military. There are humans are put into slavery and are held imprisonment. Also there are humans that are experimented on and created into cyborg 'hybrids' like Dillon.
Kamen Rider Dragon Knight
Ventara is the Earth's parallel dimension, a world destroyed by the evil alien Xaviax. The Ventara Kamen Riders fought Xaviax. Unfortunately, Xaviax stole the Advent Decks and defeated all the Riders but one, Len. Xaviax tricked mirror doubles of the original Riders to vent Len. After his dad's mysterious disappearance, Kit becomes Kamen Rider Dragon Knight. He joins forces with Len to vent the Kamen Riders, sending them to the Advent Void, in which there is no way of returning from. Xaviax searches for the best DNA in humans in order to use them for slave labor, he plans to use his mass teleporter to teleport them all to his home planet.
Similar plots to past seasons or other American Tokusatsu series
Some fans complain that there have been some similar plots from past seasons or other shows in these two shows. It is bound to happen. Just like the dinosaur theme or vehicle theme has been repeated in Power Rangers. It's common. Here are a some.
In Power Rangers in Space (1998), the Red Ranger Andros searched for his sister he lost as a child. She was kidnapped by a villain--Darkonda. His sister Karone turned out to be the main villainess Astronema, discovered through a locket by the middle of the season. In RPM, Dillon doesn't remember his past and carries around a musical locket and when he hears the twins whistling the same tune, he finds out they knew a girl who whistled it and said it came from her brother's locket, so he deduce he has a sister. He later finds a second key and unites it with his and hears the tune Tenaya whistles, making him believe they are siblings. Tenaya finds out it is true. Karone joins forces with the Rangers and then was brainwashed into an evil cyborg with short red hair. Andros had to fight her against his wishes, she got hurt but she thankfully became good.
Tenaya helped the Rangers and got kidnapped by a villain--Kilobyte and was re-programmed into Tenaya 15. So yeah, they are similar and very much alike, but Dillon is very different in personality to Andros. And Karone was raised to be evil (for like more than a decade) and wasn't a cyborg until she was brainwashed. Tenaya was brainwashed and reprogrammed into a cyborg, making her believe she was a robot within the span of a year or so. The differences between Tenaya and Astronema was that Tenaya became evil when she was older and had cyborg implants and was once blind. Astronema was kidnapped as a child, became a cyborg when brainwashed at the end and wasn't ever blind. Plus, Astronema was real close to Ecliptor but Tenaya has no real 'father-figure' unless you count Venjix but Venjix doesn't care for Tenaya and Ecliptor did genuinely care for Astronema.
Kit and Frank Taylor / Ryan and Tyler Steele
The similarity between Kamen Rider Dragon Knight has with Saban's VR Troopers (1994-1996) was that both protagonists were in search of their fathers. Differences are these: Tyler Steele helped designed the technology that led to discovering the villain and his dimension. Frank Taylor was just a pawn in Xaviax's plan. Tyler was turned into a villain robot named Darkheart and then turned good again by his son. Frank's image was used to manipulate Kit, Frank was put in a comatose state and used as a pawn. Ryan and Kit are also different in resolve. Frank is just a mechanic and Tyler was a sophistic scientist, who created the VR Trooper armor and technology.
Other little RPM similarities
- Everyone loves to point out that Venjix is the second time the name has been used in Power Rangers. That in the episode "Forever Red," General Venjix was a Machine Empire villain.
- Dome city of Corinth is similar to the domed parts of Terra Venture, the space station in Power Rangers Lost Galaxy, also with an artificial environment.
- Yes, all the vehicles are similar to those in Turbo, not exactly the same but similar.
Similarities with RPM to Kamen Rider Dragon Knight
- Like I mentioned before, the use of humanity as slave labor. Xaviax wants humans with the best DNA to re-build his home planet. Venjix uses humans as slave labor to build his machines and also uses them as guinea pigs to create cyborg hybrids.
- Arguing and conflict between warriors, well done much more in KRDK.
- The term 'robot' used incorrectly. Lacey calls the Riders 'robots' to Michelle Walsh. And Tenaya believed she was a robot, which was not a mistake on her part but was what she was led to believe.
- Memories erased. Dillon and Tenaya got their memories erased. Frank Taylor got his memories lost.
- Involvement with the government. RPM works right under the government. Dr. K, Gem, and Gema were part of a corrupt branch of the government. A corrupt branch of the government went after Kit Taylor.
UPDATED 10/26/09 1AM EST
Another thing the two series have in common is flashbacks. When each show started (in early episodes), a flashback would be shown to introduce a character or explain how the character got into the situation to have superpowers. For the Power Rangers RPM, it was one episode after another, starting with Ranger Green and ending with Doctor K. In Dragon Knight, it started a bit with Dragon Knight but more so with Incisor and every other Kamen Rider to come in, ending (so far) with Chris/Sting. We might get more flashbacks later but most likely we won't be getting any more with RPM. We did get some small glimpses of flashbacks with Tenaya and Dillon but it didn't take up the whole episode.