Class 1-A, after a long week of training. Have been granted a week of vacation by Union to a big beach. Y/n was excited to go at the beach for the first time as Momo and Mina try to countain his excitment. The bus stop in front of a huge warehouse where the class will pass all of the week in and with a private beach just for them.
Izuku:I hope everything will go well.
Mina:What are you babbling about it's just us for a week of fun what can possibly happen?!
They walk inside the warehouse and everyone gasp at how big and fancy it is.
Issei:THERE IS EVEN A FREAKING JACUZZI!!!!
He point at a large jacuzzi on the large balcony behind the warehouse.
Momo:The headmaster said that we must stay in the house or one the beach nd we can't get out of the perimeter.
Ochako:Why?
Momo:I guess it's so we don't get lost.
Denki:Seem legit. I GO IN THE JACUZZI!!!!
Mina:I you guys search for me im on the beach!!!!
Soon everyone dissapeared and were either in the jacuzzi or on the beach beside Y/n and Momo.
Y/n:Hum...What do we do?
Momo:We should set our belongings first. Come with me.
Y/n nod and follow Momo. Hey entered a room that had their and Mina's name on the door and they open it to reveal a huge california bed and many other different furitur like shelf and drawers. Momo setted her stuff and then walk in the bathroom to put on her large swimsuit as Y/n was open his luggaee only a fly flying out.
Y/n:Oh yeah right. I have no clothes.
Mina then walk out wearing her red one piece swuimsuit. It made every countour of her curve making her look even more round and cute. Y/n blush as he quickly hug Momo and snuggle in her soft and fat body like a giant marshmallow making her gasp of suprise but smile.
Momo:What is wrong with you all of a sudden.
Y/n:I just wanna hug and cuddle.
Y/n say like a kid making Momo giggle.
Momo:I know you want to but we will do it tonight ok. For now let's have some fun ok?
Y/n:Aww.
Momo giggle again and the two walk out of the house. They see the blue sky and have not a single cloud to hide the sun. Momo get in the water with the others as Y/n rest on the beach.
Momo:Aren't you coming Y/n?
Mina:Yeah she is super good!
Y/n:Hum...Ok.
He walk in the water but when he see a wave he quickly run back to the beach as everyone beside Mina and Momo laught at him.
Issei:WHAT A DUMBASS!!!!
Eijiro:Scared of a tiny wave ahahaha!!!
Y/n then look down until he have idea. He then run i side the water and then jump high in the sky and then fall toward the ocean as he take a whole new form.
Y/n fall in the water creating a huge wave that push everyone back on the beach. And now it was Y/n what was laughting.
Y/n:Aren't you guys coming?
Mineta:YOU SON OF A BITCH YOU COULD HAVE KILLED US WITH YOUR FAT A-
He was suddenly glared by Momo, Mina and Ochako who all have the large rears. Mineta then quickly shut up to save his life.
Later.
Everyone was having fun in the water and laughting and splashing each others. Meanwhile, Y/n was swimming like a dog. But he was a bit too far away from the beach as he continue swimming. Meanwhile, Toru was splashing Kyoka for the fun until she see Y/n.
Toru:Y/N WAIT COME BACK YOUR TOO FAR!!!!
Everyone look at Y/n and they see him. They try to get his attention but he was too far to ear them. As Y/n swim he was all innocent and happy...That was until a giant sea monster eat up up.
The creature that gobbled him swim down toward the abyss of the ocean as the class 1-a scream of fear and swim back to the beach.
Yang:THE FUCK WAS THAT?!?!
Weiss:IDK BUT IT WAS HUGE!!!!
Suddeny, everyone who were at the Jacuzzi run toward the group.
Denko:WHAT THE HECK HAPPENED?!?!
Shoto:A giant sea monster devoured Y/n!
Issei:Finaly.
Everyone glare at Issei.
Issei:Hum...I meant FINALY SOME ACTION!!! LET'S GET HIM BACK!!!
Momo:It's impossible. This creature is probably under a 100 if not more of the ocean. We will get crushed by the water pressure. Y/n will have to save himself.
Mina:Don't talk like he have no chance Momo. We are talking about Y/n.
Mina put a reassuring hand on Momo's shoulder.
Momo:Your right. But i jut hope he will be ok.
Meanwhile.
The sea monster swim in the abyss. It was dark and inside, Y/n was trying to make the creature explode but it was like he was immune to his powers.
(no one sing this it's just extra diegetic)
The monster swim deeper into the abyss where the sun dosen't shine. Y/n punch the stomach but it boumced back at him. Y/n then take a new form and try to slash him with his claws but nothing.
But before he could do anything else, Tentacles suddenly appear in the stomach and attack themself on Y/n immobilizing him. He try to free himself but to not avail. Outside the monster stomach, the sea monster swim deeper until there was lights at the botom of the abyss. It seemed like...A castle.
The sea monster then approach the castle. It then start twitching until it vomit Y/n out of his stomach. The monster then swim away like nothing happened as Y/n get up.
(Stop music here)
Y/n:HEY COME BACK HERE YOU....You....Where am i?
He look around him as he remove some saliva from him and advance toward the castle. Weirdly, he could breath despite still being underwater. He enter the castle and see many lost artefacts of history. The city of atlantis shrinked down in a bottle and the same go for El Dorado. The trident of poseidon, the helmet of hades and even the lightning from Zeus. He walk toward a spiral staircase and walk up the said stairs. During his ascension he see other artefacts weird looking artefacts.
Y/n then arrive at the end of the stairs and walk in a huge and dark room. When inside, Y/n look around until he suddenly ear someone.
???:Oh so you finaly arrived.
Y/n quickly turn around to shoot a laser but then it was blocked by an crystal wall. Then someone walk out of the crystal wall revealing the same chubby man wearing the weird guantlet.
Y/n:W-Who are you?
???:I...Am...Your Father.
Y/n gasp.
Y/n:Y-Your my real dad?
The man then reveal his face from the obscurity and it is revealing to be Y/n(Not the hero we expected wich will be called Y/n10 for better understanding)
Y/n10:Indeed. I hum...I know it's weird to see that your dad is a chubby man but hum yeah. That's me.
Y/n:...Why did you break my family?
Y/n10:It wasn't volontary ok! I saw your mom i liked her and she liked me and we did the thing and then boom you got here! It was just a huge paradox stuff where i came to save without knowing i also slept with your mom by returning tl the past and-GAHHH MY HEAD HURT!!!
Y/n10 hold his head in pain as Y/n blink a few time.
Y/n:It's...Hard and also not hard to believe you are my real father. But...Does that also mean you know why i can change form like that?
Y/n10 look at his son.
Y/n10:Oh that i can do. You see Junior...
Y/n:Wait my name real name is Junior?
Y/n10:Yup. Y/n Junior.
Y/n:I...Ok.
Y/n10:As i was saying. You have the ability to decompose and recompose your dna wich make you gain new forms. Problem is that you seem to be only able to recompose 50% only.
Y/n:What about the other 50%? Does it mean i simply can't?
Y/n10:Mmh i woudn't think so. Let me get something.
Y/n10 the transform into a creature and then at the speed of light he rush inside another room.
And not even a second later he come back and was holding a device in his hand.
Y/n10:With hiw thing you should be able to gain enought power to recompose the rest. And also gove you a huge power boost.
Y/n10 return to normal and put it on Y/n chest. Y/n suddenly feel a new surge of power merging with his dna as his veins and eyes glow green.
Y/n:I feel so....strong!
Y/n10:Try to transform both of your halfs.
Y/n then liberate a huge surge of energy as he suddenly transform. Inside his organism, his dna break and instantly reform into new dna as Y/ finish his transformation and was now the size of a 10 year old kid.
Y/n:I...Did it work?
Y/n10:It did! You did it son!
Y/n re transform again.
Y/n10:Now try tl recompose your dna into three ok?
Y/n nod and transform again.
Y/n:This is awsome!
Y/n10:I know right?!
Y/n return into his human form by making his dna 100% human.
Y/n:Woah so that's how it feel to be a real human?
But suddenly blue energy appear around Y/n as he start feeling weird.
Y/n:W-What's happening to me?!
Y/n10:Too much energy your gonna explode!!!!
Y/n:WHAT?!?!
But before Y/n explode, a flying object attach itself to Y/n chest and create a suit to countain the energy.
Y/n:W-What just happend?
Suddenly a voice spoke.
???:Fiewh we dodged the destruction of the universe with that one.
Y/n10:Steel! Dude you saved our butts here.
Y/n:Steel?
Y/n10:Y/n i present you Steel. This is an alien creature that i think might help with your energy surge.
Steel:Nice to meet you Y/n Junior.
Y/n:But where did that energy come from.
Y/n10:That's a hing i wanted to talk about. You see Y/n...Im not totally human. Im also part god. And the problem was that my body was not strong enought to hold this energy until i got to my adulthood. So steel kinda helpedme master this energy. And im sure he can help you too.
Steel:Yup. Hey wanna see soemthing awsome?
Y/n:Hum...Sure.
Steel:Ok! Transform into soemthing!
Y/n does as asked and transform into a flame creature as Steel cover it with an armor.
(Just imagone Steel instead of the omnitrix symbol)
Y/n:Woah!
Steel:I can create armors perfect for your new forms! Cool right!
Y/n:Yeah! Thanks Steel!
Steel:No problemo.
Y/n10:Y/n.
He put a hand on his son shoulder.
Y/n10:I may not have been present all your life. And im sorry for that. But kmow that...Im actually super proud of who your becoming.
Y/n didn't really know what to say but still smile.
Y/n:Thanks...Dad.
Y/n10:Now you should go. Your friends must be worried about you.
Y/n:Ok. Ready Steel?
Steel:Whenever you are amigo!
Y/n run outside the base and transform intk a new form that Steel cover in armor.
Y/n swim at high speed in the deep abyss and woth the armor of Steel the water pressure dosen't even hurt him. Soon he swim pass the abyss and back to the surface where it was now night time and Y/n jump out of the water to land on the beach and return to his full human form.
Y/n:IM BACK!!!
He see that no one was here. In fact the whole house ligts were close. He walm inside the warehouse and look around until he see a note on the table. He grab it and stare at it.
Steel:Aren't you reading it?
Y/n:I-I can't read this...
Steel:Is it alien writing?
Y/n:No it's even worse...IT'S....IT'S....super ugly writing.
Steel the get out of Y/n chest and grab the note from Y/n hands.
Steel:Give me that. Oh wow. You were actually right. It is bad writing. But i think i can read it. "We kidnapped your class. So if you wanna see them again. Come to this address if you dare".
Y/n:Oh no we have to save them!
Steel:Your right but we can't just go there we need a plan. Bursting in might get them killed so we need to sneak in. And i know how!
Y/n:How?
Steel:Just know that your human form isn't as useless as you think.