Ben 10 Fan Fiction Wiki
Ben 10 Fan Fiction Wiki

Sii is a shapeshifting alien from the twenty-third dimension who appears in Back in Action: Alien Universe.


Sii's natural appearance is as a glowing blue and white cube. The blue represents her shapeshifting organs and biology, while the white represents her source of energy, personality, and memory. The cube cannot be in anyway penetrated. The cubes of Sii's species would be useful as armor, but when her species dies, the blue parts of the cube, which hold together the cube as well, melts like acid. The personality and memory can be used to sustain one of her species in a temporary body.


This section is incomplete.

Powers and Equipment[]

Sii's most notable power is that which allows her to shapeshift into anything, gaining artificial recreations of her forms' powers. Mimicry of her transformations extends only as far as Sii's knowledge of their inner workings; if there are unknown functions to a device, unknown appearances under a mask, or otherwise, she will only work or look as she's imagined herself.

When she uses her powers, her forms are typically scaled to much larger proportions than normal. She normally ends up the size of most Earth skyscrapers (as Ben has noted). This has been because she's not able to concentrate enough to make her forms actual size. She shows in later episodes (such as when confronting Albedo's transformations in No Strings Attached) that she is able to control the size of her transformations.

All of her forms also retain the Bicksurians' blue and white glow. When one of her species grows older, they are able to add the species's layer of skin to hide their natural blue and white glow.

Sii is very strong, and it took Jetray's blasts to slightly annoy her. Nonetheless, through mimicking other aliens' powers, she enhances them to be as powerful as herself, which allows someone to use the mimicked powers against her by having her (for example), fire a mimicked blast at herself. (An example of this is in Infernosphere when Ben uses Sii's Aerophibian mimicked blasts against her by hitting her tail. Hitting an Aerophibian's tail out of surprise caused her to blast herself). This would shock her into unconsciousness for a short period of time, where she is locked in her normal appearance.

Known Transformations[]

  • Arburian Pelarota (Cannonbolt's species (only seen in sphere form); after seeing Cannonbolt in battle)
  • Evolved Arburian Pelarota (Ultimate Cannonbolt's species/the evolved form of Cannonbolt's species; after seeing N/A)
  • Snake (with limited intelligence; after seeing Ssserpent on the streets of Bellwood)
  • Aerophibian (Jetray's species; after seeing Jetray almost defeat her)
  • Human (When peacefully roaming Earth incognito; after seeing N/A)
  • Chelsii (Merged transformation with Chelsey Tennyson)
  • Tetramand (Four Arms's species; after seeing Tini of the Galactic Enforcers)
  • Amperii (AmpFibian's species; after seeing N/A)
  • Necrofriggian (Big Chill's species; after seeing N/A)
  • Talpaedan (Armodrillo's species; after seeing N/A)

True Form[]

In her true form, she is totally invulnerable.

Human Form[]

Sii normally uses her human form, which causes her to incur all human weaknesses, except human illnesses.



She is driven by a need to return Ben to her father King Maxin of the 23rd-dimension.

Back in Action: Alien Universe[]

This section is incomplete.
  • In Infernosphere, she is defeated by Ben as Jetray after figuring out that Sii transforms into anything powerful that she sees. She used Snake and Aerophibian disguises.
  • In No Strings Attached, she returned using a form merged with Chelsey Tennyson. She then appeared as the henchmen of a Vaxasaurian going by the alias "Overcoat," and later for a Necrofriggian going by "Cotton." She also used a Tetramand form derived from Tini.
  • In Ten Plus Twenty, she appeared in Endgame reporting on her performance on a covert mission, also sitting in on a meeting with Mistress.
  • In Man in the Stone Mirror, she returns from a mission with Scarogus and Albedo with the Rexahegon. Later, Zombozo assists her in splitting up the 10 Squad, allowing her to capture Gwen, and later Chelsey. They are eventually freed after Ben and Julie battle some foes on the Tertiary Wing.
  • In Can't Trust the Weather, Man, she debuted as Selina, a member of the Second Gynurans, alongside Cash (as Comedy) and JT (as Tragedy) in a failed fight against the rampaging Hurricane Vance.
  • In Plight of Pinocchio, she briefly appeared carrying drinks over for Cash and JT at the Nasty Burger.
  • In Escalation, Selina fights with the Second Gynurans against the Omega Squad. After Eli and Aion depart, though, she uses her normal form to defeat everyone and capture them.
  • In Malevolence, acting as Selina captured by Scarogus, she goes along with Ben's rescue then ensnares everyone in the group before trapping them in an impenetrable barrier before making off with Malevolence, Vilgax, and Scarogus.


Back in Action: Alien Universe[]



  • Out of all of her transformations, Amperii is the only transformation that mixes Sii's own name into the equation. (Chelsii does not count as it was a merge rather than a transformation.)
  • She has a "beautiful," high-pitched voice in most of her forms.
Created by COLOR
Alien Universe (BTAU - BiA - SiC) - Clad in Darkness - Benjection - DC's Hero of Heroes
Episodes and Shorts of Back in Action: Alien Universe
Season 1 Infernosphere - Limited - Magikfest - No Strings Attached - The Sea's the Limit - Hit and Miss - Dial Z for Zombified - Ten Plus Twenty - Happily Never Happened - Missing Link - New Girl - Revelation - Man in the Stone Mirror - Threat or Menace - The Alternative - Why Am I Here? - Love Stuck - Ultimate Solution - Overcoming Adversaries - Ledger Recon - Welcome to Chronospect - Prelude of the Unleashed - Ben 10: Alien Universe Unleashed
Season 2 Meet the Replacements - Hooking Up With the K's - The Armaggedroid - Fate of the Helpers - Madame Regle - Leaked - Shades of Dawn - Foreverlasting - Can't Trust the Weather, Man - Plight of Pinocchio - Maximum Slumber - Dusk - Escalation - Malevolence - Never Set in Stone
Season 3 Adrift - Marooned - Hall of Mirrors - Benjamin's Island - Skeletons - ...Enjoy Such Liberty - Welcome to Omnitropolis - Time is of the Essence
Shorts Meet the Fans - Operation Pyros - Moira's Presents - Clock Worked - Unity Broker - Why Did the Chicken Cross the Road? - Azmuth's Plumbing - Zennith, Creator of the Omnitrix - The Great Tram Robbery
Unique Aliens in Back in Action: Alien Universe
First used by Super Ben (Assault Omnitrix) Obsorber - Nigester - Plastikitee - Anos - Streak - Bugbite - Muckslide - Autosassin - Ultimate Upchuck - Clinger - Healding - Alkamine - Brawnoceros - Combustiball - Cardstruct - Dreadsense - Frisbit - Koldiak - Plasmodic - Seismix - Wavelength - Warrock - Fetterwing - Suctionrupt
Majestic Forms TBD
First used by Dawn (Alphaline Omnitrix) Vertigo - Starhavoc - Slyt - Blankslate
First used by Future Ben Atomhammer - Ultimate Brainstorm
Characters in Back in Action: Alien Universe
10 Squad Ben Tennyson - Gwen Tennyson - Kevin Levin - Julie Yamamoto - Chelsey Tennyson - Max Tennyson - Cooper Daniels - Ken
Villains Future Ben - Thep Khufan Commander - Scarogus - Dawn - Vilgax - Albedo - Malevolence - Darkstar - Sii - Elena Validus - Dr. Animo - Cyanne - Mistress - Hurricane Vance - Project Inferno - Nightcaster II - Clancy - Metalink
Supporting Characters Professor Paradox - Azmuth - Charmcaster - Eunice - Verdona - Rex - Sir George
Other Timelines/Possible Futures Gwen 20 - Upgrade Ben - Altrazon - Jennifer-Mercedes Tennyson
Groups Second Gynurans (Eli Griswold - Aion) - Omega Squad - Plumbers (Karin Frikton - Io) - Thep Khufan Armada - Board of Galvan
Others Chili - Moira Yourouguaduan