The time I was fused with my cat and sent into the Dragon Ball world

Ultra Ultimate Battle

No words are spoken, and we vanish. No matter what Zamasu does, he can't hit me. Sending him across thousands of realities with kicks and punches, I pummel him across several structures.

Zamasu crashes through several buildings in a city illuminated by neon lights, trying to retaliate but missing entirely. Firing blades of judgement towards the city, they all get pulled into my hand and form a ki ball in my hand. The red ball turns an ominous purple, infused with energy of destruction. Fused Zamasu flies back, firing a blast of energy at the attack, but I vanish from sight. A gut punch with the power of the attack sends him across reality again, sprawling like an idiot across the ground in a scarlet mansion owned by a devil. Speeding past a silver haired maid, I grab Fused Zamasu and blast him with pressurised air from my hand. Ignoring the maid entirely, I kick him into another dimension.

Moving across space as we cross a battle between glowing green ring wearers and yellow ring wearers, Zamasu tries to strike, only to miss and get hit with thousands of blows a second. The balance is stable, but both powers grow with every second to overwhelm each other, making the technique ever growing. Zamasu tries to counter, only to get gut punched into the 4th dimension for a moment, dulling our senses into nothingness, but that only makes me more effective. The balance of both powers shakes the dimension as the confused and blinded Zamasu gets his senses back suddenly, experiencing sensory deprivation, making the return of senses a sudden huge burst of pain as he screams in agony. The fused body was disrupted.

Soulscape.

The version of me and Zoom punch the disoriented Fused Soul into the ground, fighting with no mercy and fueling themselves with deep rage.
"Give us back our body!" The counterpart of me roars, grabbing Fused Zamasu by the hair and gut punching him. Zamasu recoils and drops, getting clawed at by the Zoom counterpart and damaging his soul. Zamasu bursts an aura, blasting them back with a wave of energy.
"Insolent worms! I won't lose to mortals and anomalies like you!" He shouts back in burning rage, destroying the soulscape and shattering it into floating islands.

Unknown place.

Zamasu rolls across the ground as reality crushes down around him. A broken world that melds several realities together, floating in a group of islands. Stopping himself, he slowly rises up into the air with a glare, a halo of pure light forming behind him. "You think this stops me?" His eyes flicker with insanity, this fight pushing his mind to his limit. "You think I won't destroy everything in one blast? You think I won't destroy everything here?!" Zamasu flares a bright white aura, growing extremely unstable mentally. His eyes dilate with insanity. His rage keeps growing, his mind broken completely.

A blur of blue slashes at Zamasu, but doesn't hurt him. A man wearing blue and black with white hair, his eyes flickering with annoyance.
"Is that not strong enough?" He questions as he moves back, feeling my approach. He moves out of the way just in time as I hit Zamasu with a heavy punch.
"Now what's a son of Sparda doing here?" I ask with a calm and curious tone, sending Zamasu flying with a blow that shakes his soul, then turning to look at Vergil. He looks on with some surprise but also intrigue. He's actually impressed by the power output I have and looks at the situation.
"I was searching for more power when this happened." He responds, calm as he sheaths the Yamato. "Care to explain?" I sigh, firing a condensed blast at Zamasu and burying him under millions of Kachin blocks infused with energy of destruction.
"Someone stole the body of another timelines me, planning to destroy all mortal life." I explain in a quick and calm way, knowing this mad God won't be held down. "He then fused with an immortal version of himself with his original body, making this half immortal fusion. It should be at least, but I can't be sure with the triple soul situation in that body." With a sigh, I watch the blocks explode. "Well, that didn't keep him down. How frustrating. Anyway, I need to deal with this." Vergil takes a moment, seeing that this fight isn't going anywhere with a 1v1.
"Do you have anything that can remove part of his soul?" He asks with a serious look, having an idea.
"I do, but I need time to make it, along with a lot of energy." I respond, calm and collected. "The Spirit Bomb targets the evil in one's body, but I can make it stronger and more condensed into the attack from a fusion. The Stardust Breaker. It can erase all the evil it hits, but I can't make it work under these conditions without a Spirit Bomb." Vergil takes a moment of silence, then cuts through the silence as I keep burying Zamasu and firing blasts.
"How about I get you that energy?" He suggests, drawing the Yamato and transforming into Sin Devil Trigger. "Since I can open space, I can make these open rips places you can reach, assuming you have telepathy. I'll keep this god at bay." With a slash of the Yamato, he vanishes. Rising into the air, I raise my hands into the sky and spread my telepathy over each reality.

Across thousands of worlds, everyone hears a voice they don't recognise, but it's mine.
"Please, everyone who can hear me, raise your hands and share your energy with me!" I call out across reality, people turning and looking around, confused. "Look to the skies. You'll see what's to come if you don't lend your energy!" Everyone in every reality looks to the skies, seeing as Zamasu stands up, blinded by rage and insanity.
"All mortals will die in one single attack! I'll destroy all of you!" He declares with a manic grin, the halo of light shattering as he rises into the sky.
"Please! Lend your power! Raise your hands!" I shout through telepathy, Vergil still fighting off Zamasu. He's not doing too well, though. Losing Sin Devil Trigger, Vergil moves away as he holds himself up with Yamato. Zamasu grins with malice, raising a single finger and forming a massive energy sphere.

At that moment, trillions raise their hands.

A massive Spirit Bomb takes form in the cracks across reality. My body on instinct absorbs all the energy from it. Everything trembles, reality threatening to collapse under the weight. Zamasu spins around and looks at me, sensing the energy and regaining sanity in an instant.

Silence covers everything alongside darkness.

A roar erupts, light returning in a storm of energy. The glow of my eyes becomes so bright it becomes a blazing aura.

The conditions have been met.

Raising a single hand as I take a single breath, a rainbow sphere forms in my hand. The pressure coming from it opens the cracks in whole. Every reality sees it as I close my hand, closing the gap quintillions of times faster than light. A single blow goes in. I stop my movement, spinning around and watching patiently. My body returning to normal, I revert to base.

Silence covers everything again.

Zamasu explodes in light with a scream, a pillar piercing the heavens.

When it clears, there's no Zamasu, but another me with the same fused body. He opens his eyes, the mix of relief and guilt clear.
"Thank you, but I can't stay here." He says, leaving no room for argument. "Though Zamasu himself was destroyed, the power left behind is within me still. I can't stay knowing that." I take a moment, then nod.
"Just know that you can use that power for good. How another used it doesn't define you." I tell him without a calm expression, understanding the situation as I eat a Senzu Bean and heal myself. "Know you're stronger than you think. You've got powers beyond your own understanding. Use them for good." The restored me nods, forming a time ring and vanishing through a portal. I sigh, looking at the damaged realities. "So much damage... not even the Super Dragon Balls could fix this. All I can do is wait." Vergil steps nearby and looks at me.
"You've won, but at what cost?" He asks, looking at the concern on my expression. "You seem unsatisfied." I take a moment, then sigh.
"I'm glad I was able to win, but this damage was extensive." I respond, looking at him, then staring at the many realities, knowing people can hear the conversation. "I'm happy so many people were able to unite to help defeat Zamasu, but this damage isn't what I wanted. I wanted to limit casualties and damage to something that could be restored. It'll take time for everything to repair, but it'll fix eventually."

Present timeline.

Appearing with Goku, Vegeta, and Gato from the crack in reality, I seal up this crack. Beerus and Whis, having seen the entire battle, become panicked and serious, respectively.
"What the hell was all that?!" Beerus shouts in panic. He saw the entire battle, and he's panicked. "You destroyed reality and rebuilt it off pure energy! What the hell were you thinking?!" Whis floats over, bonking me on the head with his staff.
"You were able to fix some of the damage, but you still did a lot." He says, his expression and tone serious. He then smiles. "You were able to surpass the true creator of the multiverse in that state, however, and that makes me proud of your growth. I trained a strong student." Beerus smirks, standing up.
"You seem to have also figured out that power as well." He comments, stretching as he flares his aura. "Let's see what you've got." With a calm expression, I transform into MDD, the serene and destructive aura perfectly blending together into immense pressure and heat.

The ensueing fight ends up being stopped by the Grand Priest himself, as the battle would've destroyed the multiverse. Me and Beerus are truly equal in power now, and a new gap will be born over time.