Ben 10 Fan Fiction Wiki
Ben 10 Fan Fiction Wiki
Spoilers Ahead!
This page contains hefty spoilers regarding Mercedes Barnes in Seasons 2 of Back in Action: Alien Universe.
"Dawn" redirects here. For the Season 1 bounty hunter, see Dawn (bounty hunter)

Mercedes Barnes was abducted and transformed into Mistress after receiving Azmuth's incomplete Alphaline Omnitrix, then moved to Bellwood under the guise of Dawn.

She features in Back in Action: Alien Universe.


In her debut in New Girl, she is depicted as a "blonde dimply country girl, dressed in blue overalls and plaid red and white underneath."

As the second generation Mistress, she looked like a mutated version of herself. She wears armor created by Thep Khufan scientists.

Later, in Hooking Up With the K's, to match her more closed-off nature following brainwashing by the Thep Khufan Armada, she has completely transformed to sporting all black, from her hair to sweater and pants.

In Maximum Slumber, her true form under her ID Mask is revealed. Only her face is described, as being "scaly, bumpy, and thrashed as though she’s aged decades and fought ten bears in the last few seconds," but the same texture applies to her entire form as she has been drained by the Alphaline Omnitrix.

Following the events of Dusk, her body has begun to recover, though she now possesses an unnatural form of heterochromia iridum, giving her one "golden" and one "violet" colored eye.



Before her brainwashing, Mercedes displayed an overly enthusiastic, extroverted nature combined with childlike curiosity. She was swift to share her discovery of the Alphaline Omnitrix in her backyard with her tightly-knit family.


She is very closed off and monitored by Dawn.


After moving with her family to Bellwood before Hooking Up With the K's, she has shown lingering effects of her transformation into the infamous Mistress from her time with the Thep Khufan Armada - being cold and rather ambivalent with the mention of Scarogus.

Unlike most, she wasn't initially fascinated by Ben's heroism, though with time and proximity to him, she seems to be at the very least interested in Ben as a person.

She leans closer to ambiversion or introversion now as well. In Madame Regle, Gwen seemed to have tapped into Mercedes's memories of being Mistress. Though the former has sworn to secrecy, Mercedes's reluctance to share is likely in fear of losing Ben.

She notes that she isn't as close with her family following the effects of her time as Mistress.

Powers and Equipment

Unnamed Omnitrix

As of Escalation, she wields an unnamed new Omnitrix that has the caveat of a 10-minute timer akin to the prototype Omnitrix in the original series.

Alphaline Omnitrix

Main article: Alphaline Omnitrix

Up until the end of Dusk, she was equipped with the Alphaline Omnitrix, giving her access to a suite of alien transformations both old and new. She was also unfortunately afflicted with a deadly disease brought about by Alpha, the dangerous power source Azmuth employed for that experimental Omnitrix. She had technically been an EVO for some time, until Healding cured the affliction while reviving her.


Back in Action: Alien Universe

This section is incomplete.
  • In New Girl, she finds Azmuth's latest invention. After attempting to figure out what it is, half of her home explodes with her in the thick of things.
  • In Man in the Stone Mirror, during Endgame, she is mentioned as having gone missing despite the events of the explosion being revealed.
  • In Ultimate Solution, she captured Scarogus and another of Thep Khufan Commander Tersce Tenebrosi's men.
  • She first appeared as Mistress in Ledger Recon.
  • Her first mission, where she joined the Thep Khufan Commander, was in the following episode, Welcome to Chronospect. Her fate was initially unknown.
  • In Hooking Up With the K's, she returned very close to the end and met Ben Tennyson.
  • In Madame Regle, she met Gwen and Kevin.
  • In Shades of Dawn, she appears for the first time masquerading as the male villain from Season 1 Dawn also partnered with Darkstar.
  • In Can't Trust the Weather, Man, she concocts a plan to give Senator Vance Vetteroy weather powers, involving springing Dr. Animo from his Plumber captivity. They later end up controlling Vetteroy's mind, and Dawn states the whole ordeal was simply to partner with Animo to an unspecified end.
  • In Plight of Pinocchio, she was briefly spotted attempting to breach the energy barrier in Bellwood to reach Azmuth.
  • In Maximum Slumber, she is a person-of-interest in the poisoning of Max Tennyson and a group of new Plumbers. During Azmuth's interrogation of her, he admits he knows now that she is Dawn.
  • In Dusk, after Azmuth says that he cannot repair the Alphaline Omnitrix, she runs from Ben to enact her backup plan with Darkstar and Dr. Animo. In doing so, she ends up meeting Darkstar's parents and learning of his origin, then getting rid of the Alphaline Omnitrix and her disease by Ben as Healding.
  • In Escalation, she tags along for the mission to keep the Plumbers on Earth, eventually coming to help save innocents at the episode's end.
  • In Malevolence, she initially was helping with the evacuation effort at the damaged UN Headquarters in NYC. Later, she joined back up with Ben in NVI, alongside Chelsey, Gwen, and Kevin, and used Healding to revive JT.

Seventeen in College


Back in Action: Alien Universe

Seventeen in College


  • In Ten Plus Twenty, Gwen 20,000, an alternate timeline future for an Omnitrix-wielding Gwen, has a daughter named Jennifer-Mercedes Tennyson, who she claims is named from her future best friend (across both that "Gwen 20,000" timeline, and Earth-69).
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