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

Immortal Ally and Chosen Paths

Teleporting over to Zamasu, I look at the Dragon Radar in his hand.
"I see you've got a plan." I say to start off a conversation, deciding to get to the point. Zamasu nods.
"Yes, It's a last resort, but..." He responds, taking a moment to think about how to say this. "If I were to become immortal, I could be helpful." I take a moment to process what he said, then nodding and allowing him to continue. "It'll be a last resort if you can't win, but I want to keep it in mind." I take a moment, then relax.
"Alright, Zamasu. I'll trust your judgement." I say in response, calm and collected. "I need to reign in my destructive energy as a form, anyway, so I'll do that while the time machine is being refuelled."

Time Chamber.

Destructive purple flames flicker around me as I meditate, the aura flickering in and out, bursting out and calming.

The door opens, Goku and Vegeta stepping in.
"Training already?" Goku questions at the sight of my immense power. "The amount of ki you have is insane! The trip through the multiverse sure made you strong." My eyes open, the aura fading as I do so. Standing up in base form, I look towards the two.
"Yes. Whis won't be training us since time travel is involved, so I need to work on this form myself." I respond with a calm demeanour, staring at the two Saiyans. "I want to control my energy of destruction if we want to win against my counterpart. Ultra Instinct seems to be out of reach for now, but I feel its close." I take a moment, then sit down. "If you want to train here, I can ask Whis to put me in his staff." Standing up, I walk to the chamber door and step through, leaving Goku and Vegeta to train.

2 hours later.

Whis watches his staff flickering with silver light and purple flames as my body shifts between two techniques.
"He's trying to use Ultra Instinct and the power of a destroyer at different intervals." Whis comments as Beerus glances over. "He's trying to access both, but it isn't easy as that. He's straining." Beerus' eyes focus on the staff, seeing the flames and shimmering shifting.
"I wonder if he'll reach mastery over that." Beerus comments, watching my miniature form within the staff as it moves between techniques.

Suddenly, both silver and purple glow at the same time within it, two forms now within it. "What is that technique...?" Whis smiles.
"The Yardrat Cloning technique." Whis answers, watching my real body using energy of destruction as the clone tries to manifest Ultra Instinct by calming himself. The silver and purple crash against each other, the clashing energies causing pressure to release from the staff. "Oh my, he's trying to merge back with the clone and use both powers in the same body."

As the clone and myself merge together, the unstable mixing causing immense strain. A scream echoes from the staff, then both light and flame vanish. My now unconscious body is released from the staff by Whis, collapsing on the floor of Capsule Corps backyard and being healed. When I wake up, I stand up with a sigh.
"I guess my body needs more time." I comment as I look at Whis. "How long did I last this time?" Whis looks at the timer.
"34 minutes and 28 seconds." He answers, allowing me to note down the time of the session. At the same time, Bulma comes out with fuel for the time machine.
"The fuel is ready!" She shouts as he rushes to the time machine, swapping the empty fuel canister with a full one. "I've already told Goku and Vegeta, your future self is ready too!"

Future me steps out from the building, his expression calm and cold.
"Shall we begin? I've prepared extra so you and I can go as a duo ahead of time." He asks with a relaxed expression, looking at me as I nod. Taking out a capsule, he throws it down. The second time machine pops out, having been reconstructed through the work he and Bulma did.
"Let's get going. Goku and Vegeta can be sent by Bulma." I respond to my future self, calm as we step to the time machine. Opening it, we hop in and set the machine for travel.

In the future, Black grins as he looks down at the flaming city.
"The more I learn, the stronger I become. Come, William Carter-Tindale. Show me how strong I can become." He says to himself with a chuckle, then laughing out.