You were currently flying with Son after detecting a strange energy from the east. You thought that a foe like this would be a good chance for Son to test his skills.
Son: Hey, Big Bro, I was wondering why you didn't let S/N come along...? You've been training him fairly well and this could be a good challenge for him.
Y/N: This isn't just any foe, Son. This is a Celestial. You're lucky that I'm letting you tag along with me. Son isn't ready for this type of opponent.
Son: Alright...
Y/N: Anyway, Their just up ahead, no matter what happens, stay on guard. We don't know what this person is capable of.
Son: Got it.
With that the two of you flew off into the distance and prepared for battle. After roughly a minute or so, you reached an Island. This is where this energy was residing.
Y/N: What would a Celestial be doing all the way out here...?
Son then also arrived on the scene as you flew ahead of him by quite a bit. Looking around and not seeing anybody.
Son: Are you sure that this is the place...? I don't sense anything...
Y/N: Remember what I said, Son. Always stay on guard.
You closed your eyes and started to search for this entity. It was clear that they were hiding their energy. But even you were having trouble identifying them.
Y/N: ...
All of a sudden the water started to swirl about when a man came flying out from the deep blue depths. Charging straight at you without warning.
Son flew back a bit to gain a safe distance as this man started his attack. Sending a barrage of punches and kicks your way to which you blocked or dodged each blow.
This foe then had you land back onto the ground to which he also landed along with you. The two of you facing each other, roughly 20 feet away from each other in a stare down.
It was here where you managed to get a better look at this guy. He was a Saiyan, just like you. And a Celestial if it's worth adding. Besides his aura, there wasn't anything unusual about this guy aside from the fact that he had several tails instead of only one.
???: I wasn't expecting you to show up, Traitor...
Xoya the Celestial
Y/N: "Traitor?!" Who do you think you are?!
Xoya: My name is Xoya, As a Celestial it is my duty to eliminate all Saiyans who wield godly energy!
Son: Hey, Bro! What's this guy's deal?!
Y/N: I'm as lost as you are...
Xoya: Are you truly that careless as to forget the Vow of our people, you so called "King"...?
Y/N: Don't call me that! I'm Y/N L/N! Celestial Protector of the Multiverse!
Xoya: Lies! Do you truly wish to run away from yo ur title as King?! COWARD!! Where is the Gate Keeper?!
Son: Lotus...?
Y/N: He's none of your concern!
Xoya: LIES!!
With that the battle began, the two of you started trading blows, but Xoya seemed like he couldn't quite keep up with you. You grabbed him by one of his several tails and threw him across the field.
Y/N: Son, Tag in!
Son: Got it!
With that you leaped onto a nearby cliff side and let Son step into the fight. He wasted little time in charging Xoya as the two of them traded blows.
Son and Xoya were more evenly matched. Although given by his looks, Xoya was a full grown adult, and Son was still in his teens, giving Xoya the advantage in experience and such.
The two of them kept fighting, but Xoya using some tactics that not even you had seen before, started to outdo Son in their duel.
Son started taking blows left and right. A punch to his cheekbone, and then a kick to his hip, and finally a classic gut punch to end his combo before he sent Son flying back with a Ki blast.
Son began to grit his teeth as he then started to glow a little bit before letting out a loud scream and shaking the entire island.
Son: Grr...HAAA!!!
All of a sudden Son started to emit a bright light from his body. Undergoing his Super Saiyan Transformation as Xoya was sent sliding back a few meters.
Son: Playtime is over!!
Xoya: That glow...that is the Transformations that the lower versions of the Saiyans would fashion...pitiful! Pitiful! Pitiful!
Son: Then come and see for yourself!!
With that, Son dashed at Xoya at rapidly increasing speeds, launching Xoya's body into the air with a devastating uppercut to his chin.
Son then leaped into the air and began to lay quite the pummelling upon the Celestial Challenger. Knocking him left in right in the air before knocking him back into the ground with a powerful leg drop kick.
A large crater formed in the Center of the battlefield as you watched and studied Xoya's techniques and fighting style.
Y/N: Son really has stronger. Good.
All of a sudden in the midst of the smoke and dirt, a large barrage of Ki blasts erupted from the crater as Son was nearly caught off guard by this.
He then flew to the left while dodging all of Xoya's blasts. Son balled his hand into a tightened fist as it started to grow upon his firm grip.
Son: Keep your cool and have a watchful eye...When he gets tired from launching so many Ki blasts, that'll be the opening I need...
Eye-Catch
Eye-Catch
Son then noticed that Xoya's muscles and limbs were starting to twitch and crack, Xoya growled in slight pain before Son went wide eyed upon seeing his opening.
Son: There!!
Your younger brother than closed the Gap between him and his opponent in the blink of an eye as his fist was now coated in a yellow aura, driving his fist clean into Xoya's stomach.
Y/N: A Ki infused punch. Not bad, Son. Not bad at all...
Xoya: GAAAAH!!
With that Xoya was then flung into the ground as he left a long trail of the destroyed terrain behind him. By the looks of it, Son had won this battle.
Son then reverted back into his base form as you touched down next to him and gave the teenage boy a pat on the back.
Y/N: Good job, little bro. Let's head back to I-Island and call it a day. I'm starving!
Son: Alright! I won!!
With that the two of you were about to leave when a massive pillar of orange Ki erupted from the ground. The two of you turned around with wide eyes as you felt Xoya's power increase over a thousand fold.
Son: That was my strongest attack! How could he still be in one piece...?!
Y/N: Ugh...I should've known that it wouldn't have been that easy...
You then went wide eyed as Xoya was then right in your face as he threw a powerful punch towards your chest. You managed to blow it at the very last second but you were still sent sliding back from the impact.
Son: Are you okay?!
Y/N: Yeah...He's stronger...MUCH Stronger...this is starting to get dangerous...sorry to spoil your fun, but I'm tagging back in.
Son: No arguments here!
With that Son leaped away to watch from a safe distance, but so long as he was standing on the Island, his safety wasn't guaranteed.
Y/N: Just what are you...?!
Xoya: I am Xoya the Celestial! I will be the one to purge all God Saiyans, and I will crush anybody who dares stand in my way!
With that little speech, you were starting to put the pieces together. You remembered something that Kalasha and The Grand Priest told you about years ago.
Y/N: The Priests once spoke of a war between Celestial Saiyans and God Saiyans that lasted for entire Generations. He must be after Lotus because he's the strongest God Saiyan!
Xoya wasted no time in attacking you as he was now too powerful for you to battle him in your base form alone. Quickly transforming into a Super Saiyan before clashing with the Celestial.
The two of you locked hands and arms as you started to push each other back. The entire planet began to crumble before you as you gritted your teeth and blasting Xoya with a Ki beam from your foot.
This sent him flying back as you then sped towards him and started beating him down. Xoya did his best to defend himself, but you were too fast.
However, you noticed that he started to growl violently, his surge of energy suddenly skyrocketed once again as he sent you flying into the clouds with a single punch to your face.
You were quick to recover, but you were still baffled as to the fact that Xoya's power was rising so quickly.
Y/N: He powered up again...how does he do it...?!
Xoya then started to growl and power up as you noticed this and prepared yourself for the upcoming attack.
Y/N: At this rate, even Super Saiyan God won't be enough...
You then transformed into Super Saiyan Blue and charged Xoya as he did the same. The two of you clashed fists and started to shake more than just the planet.
Son was nearly blown away by all of the shockwaves and wind pressure caused by your clashes.
Xoya: I WILL KILL YOU!!
Y/N: Tch!!
The two of you then started to trade blows once again as the entire planet was started to fall apart. You were still using Ki control during the battle, but Xoya was slowly started to drift away from controlling his power. The only thing on his mind was that he needed to strike you down, no matter the cost.
You then punched Xoya in the face hard enough to put him in a daze. You were about to blast him at point blank range with a Kamehameha when he suddenly snapped out of it and grabbed you by the neck.
He started to choke you as he then flew straight down with your head facing against the ground, Son was quick to follow the two of you as you and Xoya crashed into the water.
Y/N: GAH!!
Son: Bro! Hang on!!
Son could notice particles of Genkai energy sparking from the midst of the giant splash. Once the mist settled, the two of you were seen struggling against each other on the now exposed sea floor.
You had been forced to step into Genkai Deity on top of Super Saiyan Blue against Xoya as his power was simply increasing too rapidly. But not only that, he was also becoming more resistant to you attacks. So you had to step up your game big time if you were going to win this.
Y/N/Xoya: GRRRAAAGH...!!!
Son: Genkai Deity!
Xoya: What...?! What is this?!
Y/N: HAA!!
Xoya was then hit with one of the hardest punches that he had ever felt in his entire life. Your fist smashed right into his face, split the clouds and the stars in space before Xoya was sent out of orbit in seconds.
He went so far to the point where he went right through the moon and took out a massive chunk of it. Now the moon of Midoriya's world looked almost identical to that of Ruby's world.
Son: Did you do it...?
You remained silent for a moment while staring at the now partly shattered moon. About 20 seconds passed by before you finally have him an answer.
Y/N: No. He's coming back at untamed speeds...I think it would be best if you leave and regroup with the others.
Son: What?! And leave you with...that?! No way! He's insane!! You won't be able to beat him on your own at this rate!
Y/N: Trust me...it may look like I'm at my limit...
You then started to emit white energy along with your Genkai Ki as the red Omni markings flashed onto your body.
Y/N: But I still have LOTS of power left to display...