Several years passed after Trunks became the new king of the saiyans, and in that time, many things changed. The saiyans had completely stopped their planet conquering, and in return had become a very religious race, building dozens of temples to God all across the planet. Trunks also trained the saiyans, teaching all of them how to become super saiyans and making their base forms stronger than many of Frieza's suppressed states.
This was good, as Trunks's plan to spare Frieza had unfortunately backfired, because soon after being forced to flee Planet Vegeta (now once again Planet Plant), he had declared war on the planet. Not only that, but his soldiers had become much stronger than before to the point that they could actually match the saiyan's base forms. Some were even capable of giving a fight to the super saiyans.
Trunks didn't know how they had become so strong, but hoped that Frieza hadn't become much stronger. Speaking of Trunks, he had decided to take King Vegeta's wife as his own, and together the 2 had a son that the boy's mother named Vegeta. Trunks thought it was weird to technically be his stepfather's father, but it was better than him not being born.
However, he knew that the time had arrived. His father would be born soon, so he had had some spies investigate the parents of Raditz. Once he was informed that their second son Kakarot had been born, he quickly set out to their house with no hesitation. Once he landed, he was greeted by Bardock, who asked,
"My king? What brings you here?"
"I need to see your new son."
"...What for?"
"I need to see him. Let me through."
Bardock agreed, but was left cautious of Trunks's motives by his way of speech. The half-saiyan entered the home and made his way to little Kakarot's crib. It was situated right next to the bed where his mother Gine was sleeping, still exhausted from giving birth. Trunks looked at the baby Kakarot in his crib and quickly scooped him up. Unfortunately for the future warrior, Gine just so happened to awaken at that moment, and saw the stranger stealing her son.
Not realizing that this was her king thanks to her tired state, Gine yelled,
"You! What are you-?!"
Before she could finish her sentence, Trunks knocked her out with a light chop to the neck. He told the unconscious saiyan woman,
"I'm sorry, but this is the will of God!"
Hearing the commotion, Bardock ran into the room to see the king holding his son and standing over his unconscious wife. Trunks took a glancing look at Bardock and then flew off, the saiyan father flying after him. Trunks saw this and fired a ki blast at Bardock to get him off of him. However, Bardock powered up to super saiyan and deflected the blast, yelling,
"GIVE ME BACK MY SON!"
He then fired a spirit javelin at Trunks, but the half-saiyan king didn't react one bit to the blast. Instead, he turned around and yelled,
"You fool! I'm doing this because God wills it!"
"I don't give a crap about God's will or whatever! I won't let you take my son!"
"...You always were the rebellious type, grandfather."
Before Bardock could react to being called grandfather by Trunks, he was blasted out of the sky by a ki blast from the king. Trunks was then able to make his flight to the palace uninterrupted. As Bardock struggled to his feet, Gine arrived, having regained consciousness and flown to her husband as fast as she could. As Bardock stood up, GIne asked him,
"Where's the king taking Kakarot?!"
"From what I can tell….the castle. Come on!"
Bardock thanked God that Trunks had taught all saiyan warriors how to sense ki. The saiyan couple quickly flew to the palace, where they saw Trunks putting a still sleeping Kakarot into a space pod. The saiyan king told his future father,
"You are destined for great things, Goku."
However, Trunks then sensed the kis of Bardock and Gine. He should've expected that they wouldn't give up. As the 2 saiyan parents landed on the ground, Trunks told his personal guards,
"Restrain them."
The guards did so, one of them powering up to super saiyan to hold Bardock back. As she and her husband struggled against the guards, Gine asked Trunks,
"Why?!"
Trunks turned to her and simply said,
"It is the will of God."
He then activated the spacepod, which shot up into space. Gine cried out for her son, while Bardock was left absolutely enraged. His power spiked and his muscles briefly bulked up with his hair becoming more wild, allowing him to break out of the guard's hold and fire a ki beam at Trunks. This blast was simply deflected however, as Trunks then told the guards,
"Throw them in the castle dungeon."
The guards departed with the 2 saiyans in tow, and Trunks then looked to the sky. He knew this was the right choice.
"And that brings me to now. I chose to arrive at this time specifically because it was when Uncle Raditz arrived on Earth in my timeline. Speaking of which, he's waiting for me back at my ship. Father, with your help we can surely defeat Frieza and bring peace to the universe!"
Goku just stood there silently looking at the stranger, who he could somehow tell was telling the truth. He told the future warrior,
"Ok, so ignoring all the other stuff you told me, the only reason I'm on Earth is because you basically kidnapped me and locked my parents in prison."
"Yes, but it was the will of God."
"Ok, cool. But how am I supposed to get as strong as you in a decent time?"
Trunks replied,
"The gravity on Planet Plant is 10 times that of Earth."
He turned to Bulma.
"Mom, can you make a chamber that can regenerate that level of gravity?"
Bulma winked and told her future son,
"Why, of course!"
"Good! Now let's go!"
Trunks and Goku then flew off, Goku grabbing Bulma and present Trunks and taking them with him. They soon arrived at Trunks's spaceship and saw a man waiting for them. He was a tall man with long hair who wore clothes similar to Trunks. Trunks introduced the man.
"Father, this is your older brother Raditz."
Goku greeted Raditz, who coldly responded with,
"Hmph, we don't have time for this. Your highness, we must get going!"
"Alright, Raditz."
Goku, Trunks and Raditz then flew to Capsule Corp, Bulma and Present Trunks being carried by Goku. Raditz was a bit curious to meet his sister in law and a younger version of his king, but shoved that to the side for now. Once the 4 arrived, Bulma and her father quickly got to work on building the gravity chamber.
During this time, Goku, Raditz and Trunks trained outside together. While Trunks didn't grow much stronger from the training, Goku and Raditz increased by leaps and bounds. Once Bulma was done with the gravity room, the 3 saiyans quickly turned their attention to it and what it could do for them.
Goku was already strong enough to handle 10 times Earth's gravity, so they started from there and made their way up. Trunks also paid special attention to Goku, making sure he got up to Raditz's level as fast as possible. Eventually they managed to reach 300 times Earth's gravity, and once the training was done, Goku and Raditz were equals in every way.
After a few months, Trunks declared their training over, and the 3 made their way back to Trunks's large spaceship that was big enough to have a gravity chamber inside. Bulma was there to greet them as they left, and told Goku,
"Make sure you come back in one piece."
Goku replied;
"Of course I will!"
He then stepped into the spaceship with Raditz and Trunks. Trunks closed the hatch door and told them,
"It'll take us about a month to get to Planet Plant from Earth. All of the basic amenities we'll need are in this ship. We'll train every day but Sunday, as Sunday is a day of rest. Are you two ready?"
Goku and Raditz nodded, and Trunks replied,
"That's what I like to hear."
Trunks pressed a red button on a console, and the ship lifted up and shot into space. Bulma watched as it disappeared from sight and said mentally,
'Goku….good luck.'
Power levels
King Trunks (suppressed on planet Vegeta): 1,000,000,000
Average saiyan during Trunks's reign: 1,500,000-2,600,000
Bardock (King Trunks Reign): 3,000,000
Baby Kakarot: 2
Gine: 1150
Bardock (Super Saiyan): 150,000,000
Bardock (Super Saiyan Grade 2): 264,000,000
Raditz: 1,200,000 (Raditz can't quite go Super Saiyan yet)
Goku and Raditz (Post gravity training): 109,200,000