He killed them all...she lost to a maniac...both are poor lost souls. Fortunately, the Continuum Shift seems to think them still useful. Given a second chance in a new world, the two will aid in a rebellion against a tyrannical dictator and return the throne to its rightful heirs.
Omniverse Underground
is a crossover between Ben 10, Sonic Underground and BlazBlue written by Gammatron and Seanzilla1988 in which Ben Tennyson and Makoto Nanaya somehow end up on Mobius after unknown series of events and a near fatal encounter with Hazama respectively. The two quickly join the royal siblings in their war against Robotnik, and try to figure out how they ended up there in the first place.
Similarly to the authors' other works, elements of other series are also introduced as the story goes along, as well as other continuities for the Sonic side of things.
Omniverse Underground provides examples of:
- Adaptational Angst Upgrade: It's not clear what happened to Ben before he arrived on Mobius beyond the fact that he did not go through the events of Ben 10: Ultimate Alien, however it's heavily implied that the Forever Knights were significantly more ruthless and went after his family. Later chapters imply that he went just as dark in stopping them, and holds significant guilt in the present.
- Adaptational Intelligence:
- Dingo has become significantly more intelligent in this version, going from a Dumb Muscle to a competent tracker, and is mentioned to have successfully caught several Freedom Fighter groups.
- Ben is noticeably more mature and tactical here, being more tactical with what forms he uses rather than favoring his heavy hitters. He also makes frequent use of Gray Matter between missions to work on the groups gear and dedicates time to pondering any ongoing mysteries when in the form, showing off his Super-Intelligence more. And he apparently learned Japanese from his mom's side of the family.
- Adaptation Origin Connection:
- Rachel Alucard mentions that the Oracle of Delphius was one of her magic instructors before the story began.
- It's revealed that this Ben has actually met Ragna before during a previous summer (in addition to Jubei, Rachel and Valkenhayn), and outright admits he sees him as an older brother. In the flashback, Max has apparently helped out Rachel and Jubei before, suggesting he's been to the Blazblue timeline.
- Abdaptational Villainy: Jin Kisaragi, slaughtering Roll's family just necause he considered them freaks and mutated Beastkin.
- Almighty Mom: Makaya Nanaya is clearly this, being able to keep her super strong husband and daughter in line.
- Armor-Piercing Question: When discussing Ragna's status as The Dreaded in her world, Makoto tells Ben that he destroyed three NOL bases. She visibly pauses after Ben asks her how many casualties he caused, admitting that there were none.
- The Berserker: Ben as Grimlock.
- Beyond the Impossible: Ben mentions the one time he tried to forcibly wake up Ragna when his friend was exhausted, he felt the resulting punch for weeks afterwards. Despite being Ghostfreak when he tried.
- Big Brother Instinct:
- Ragna has this to Ben, seeing him as an honorary brother and threatening Rook when the latter states he intends to arrest him. When the two reunite, he's consistently one of the few people able to get him to open up about his past trauma, and even gives him advice on how to deal with it.
- According to Alpha, Ragna extends this to Noel and Haseo, being very protective of both of them.
- Broken Ace: Ben, being an experienced superhero with access to virtually every powerset imaginable, and is even more resourceful and intelligent than his canon counterpart, even acting as The Smart Guy for the heroes. He's also harboring immense trauma prior to being put in stasis, and reacts poorly to any triggers.
- Crazy-Prepared: The rules for the Hyorinmaru clan engagement state that the bride to be must remain within a certain distance of their partner, and includes several additions for when it still applies, up to other dimensions.
- Curb-Stomp Battle: Ben delivers one to Sleet, Dingo and their forces thanks to turning into Way Big.
- Cute Clumsy Girl: The Yayoi's family maid Hina, near constantly tripping on her own feet and losing her glasses.
- Double Standard: Abuse, Female on Male: The Hyorinmaru tribes law on their Rescue Romance can apply regardless of the gender of the rescuer, but states that it does not apply if the rescuer intentionally set up the situation, and that the woman in question will be compensated in such an event. However, Miyuki only specifies the punishment for men that do this (banishment and castration), with no mention of what happens to women who attempt it.
- Epic Fail: Apparently, while driving the RV, Manic has managed to crash it into a mirage of a tree.
- Even Evil Has Standards: Sleet is an utter scumbag willingly aiding in Robotniks hold on Mobius and throughout their 'partnership' shows the absolute minimum concern for Dingo's wellbeing. Nevertheless he is genuinely saddened when his friend 'dies', and is outraged when Shockwave bluntly suggest he get over it.
- Expy: Jake, J, and Jacky (a trio of Mobian raccoons) are ones for Ed, Edd and Eddy respectively, being a Cloud Cuckoo Lander, The Smart Guy, and a greedy, wannabe Con Man respectively. They also have their own equivalent of the Kanker sisters.
- Fantastic Racism: Ben and Makoto are forced to be discrete in several parts of Mobius, owing to Robotnik giving humans a bad name.
- Foreshadowing: In the opening chapter, Kokonoe remarks to Sonic that he and his siblings are only using about 20% of their medallions true power. Much later, it turns out all three can turn into melee weapons, Sonic's a sword, Sonia's a spear and Manic's a knife or armour.
- Let's You and Him Fight: Makoto initially fights Ben, owing to just coming out of a brutal fight with Hazama, and seeing a green colour scheme on him.
- Like Father, Like Son: Celebrations III shows where several of the Remix Heart members pick up their quirks from.
- Noel and her mother have a shared love of soaps, and get upset if anyone talks badly about them.
- Makoto shares her fathers boisterous attitude and Big Eater tendencies.
- Tsubaki and her father both enjoy classical literature, while she and her mother have a scary fixation on 'justice' when enraged.
- Morph Weapon:
- The siblings medallions can turn into instrument/laser rifle hybrids, as per canon. Sonic later discovers his can turn into a sword and gauntlet based off Caliburn, and as the story progresses it's revealed Manic's can turn into a dagger and armour, while Sonia's turns into a spear and armored shoes. All three can further combine with one another when Sonic wields them, creating Excalibur Sonic.
- Roll has a sword (and previously a pocketknife) that can change form by absorbing her Wisp companion, Yacker, depending on what form he takes.
- Mundane Solution: After capturing Ben, Robotniks forces prevent him from using the Omnitrix by... putting a clamp over it.
- Noodle Incident:
- In a flashback, Jubei mentions a few involving Ragna, including one time where his apprentice nearly got the Beastkin sold to a circus. Ragna says he's still sorry about that one.
- Likewise, Ragna and Ben apparently had several in the summer they travelled together, at one point ending up in an alternate Australia that was full of things that tried to kill them like exploding trees and kangaroos with metal teeth.
- Rescue Romance: After Sonic rescues Roll, she kisses him and declares them engaged. It later turns out this is a practice amongst the Hyorinmaru tribe, with women marrying whoever rescues them from mortal peril (though it doesn't count if someone causes said danger in the first place). The triplets father Azure ended up meeting Aleena the same way.
- Shipper on Deck: Queen Aleena officially approves of Roll and Sonics relationship, even saying she's welcome as part of the family.
- Ship Sinking: Noel firmly tells her parents that she sees Ragna as an older brother, a sentiment he reciprocates.
- Ship Tease: Several couples are teased throughout the story.
- As with most of the co-authors works, Ben/Makoto.
- Sonic with his Rescue Romance fiance Roll.
- Surprisingly, Manic and Tsubaki.
- Shout-Out:
- Alpha's powers come from nanites letting him build various machines, just like the main character of Generator Rex.
- When traveling to Sin Alley, the main character run into Sam & Max.
- Several of Robotniks SWATBots have rather familiar names, including Starscream, Shockwave, Jetfire and Jetstorm.
- When the main characters visit the Oracle, he gets the group to find a spell that is a cross between music and magic.
- Noel's parents are named Daisy and Gatsy.
- Trademark Favourite Food: On top of canon examples like Bens love of smoothies, Sonics chili dogs, and Makoto for anything acorn flavoured, Manic is just as obsessed with pancakes as his brother is with chili dogs.
