All rights belong to Akira Toriyama, Toyotarou and Toei Animation
This is based on the manga cannon, so there may be some discrepancies with the anime.
"I'll do it." Goku announced, slamming his fist into his palm.
"You'll do what?" Whis inquired.
"This fusion. I'll do it."
"You can't be serious, Kakarot!" Vegeta protested, leaping out of his seat, "You just saw what happened to Keel Vegeta!"
"I know but…this wouldn't be the first time I've died."
He had been prepared to make the ultimate sacrifice before, multiple times, in fact. Only, death wasn't the ultimate sacrifice, was it. But this would be. The offering of his soul.
"Have you thought about what it will do to you?" Vegeta asked, "All the Darkness, inside you?"
"Yes, Vegeta, I know. I'll never be the same. But if it reaches here no one on Earth will be the same either, will they? You told me the saiyans acted a lot like normal humans before they fought with it."
"I think it took some time to take effect. We could delay a little. Have time to think of something else." Vegeta objected urgently. It was touching how he was trying to sway him away from this sacrifice, trying to protect him.
"It's too great a risk to take," Goku countered, "This planet, sure there are some not so nice people out there, but for the most part everyone's kind. Everything's peaceful. I don't want that to change, not if I can help it."
This earth was precious, it was his home, where he had grown up, where he had raised…well, where Piccolo and Chichi had raised his children.
"And what about your family, Kakarot?!"
But to Goku, the whole earth was his family, his biological relatives being no more important than the next person.
"They coped without me for seven years. I'm sure they can handle it."
"Kakarot!" Vegeta's face was turning red, "You didn't see how it affected them! How Gohan came crying to me of all people! How I had to give him the talk when he was older! Think about Goten, he's grown so attached to you!"
Goku was silent for a moment, trying to form his thoughts into a coherent argument.
"Look, Vegeta. Do you know what it was like when I returned? It was Trunks this and Uncle Vegeta that. Gohan was really distant; heck, Piccolo was more his father than me. They don't really need me. Besides, I'll be doing this for them. To keep them, you know, nice."
"I suppose I understand your reasoning, but it shouldn't be you." Vegeta folded his arms, turning away from his companion, hesitance in his stance. There was something deeper going on with him, but Goku couldn't figure out what.
"What? Why?"
"Because…it's my duty."
"Huh?"
"I am the last of Saiya Vegeta's line, heir to his kingdom. I am the warden of the Darkness. His responsibility falls to me. It should be I who do this, not you."
"No way!" Goku objected vehemently, "Now who's not thinking of their family?"
"I am thinking of my ancestors."
"And Trunks and Bulma? You can't do this to them. Trust me, they need you more than my family needs me."
"And should I sit idle while a Darkness drives away their character and turns them into monsters like I was?"
"And that's why I should be the one to do it."
"Gentlemen!" Whis interrupted.
"Perhaps there's an easier way to settle this…strange dispute you've got going here. It is beyond me why you should be arguing over who gets the privilege of sacrificing themselves, but nonetheless…which of you is stronger?"
Goku brightened, seeing the clear opportunity to claim victory, "It's me!"
Vegeta growled resentfully, but did not dispute this fact, except to say, "I'm not sure you could even pull it off, Kakarot."
"And you could? I'm the one who knows the mafuba."
"I could learn it!"
"Enough!" Beerus cried, "No more arguing about it! Goku will seal the Darkness away and promptly die for his troubles and everything will be fine."
"Keel Vegeta didn't die instantly…" Vegeta considered, "Perhaps if we had any more sensu beans…"
"Ah!" Goku snapped his fingers, "I'll go and ask Krillen!"
Placing his fingers to his forehead, he concentrated on Krillen's ki, popping into existence beside him.
"Wah!" Krillen cried out, lurching away from the newly materialised Goku and dropping his spatula. He quickly snatched it back up and dumped it in the sink. The midday sun glistened on his bald head through the kitchen windows as he scowled at his childhood companion. Goku hadn't been to their new house often, and was still surprised every time he went to visit Krillen and didn't end up at Kame House.
"Hey!" Goku called, smiling and waving, completely oblivious to how rude it was to just appear beside someone without any warning.
(Krillen could have been on the toilet or something)
"I was wondering if you had any sensu beans?"
That, Krillen considered, was not an innocent question.
"Why do you need sensu beans? Are you in trouble?"
"No, no! Well, maybe. See, there's this strange misty thing that we have to…imprison. Don't worry about it. But I thought we should make sure we had some sensu beans, just in case."
"Well, I could go check…" Krillen trailed off doubtfully. He turned and headed into the living room, where a still tiny Marron was watching a children's program. She seemed to be taking after her father more than her mother in terms of her height, which he thought might be unfortunate for her.
Such a wonderful, innocent family.
No, Goku did not regret his decision. He would save them, that was for certain.
But would he ever get to enjoy spending time with his friends again? He wasn't really one for catching up, sometimes going years without contacting people. Really, it was his friends who arranged to meet up with him, rather than the other way around. But he still loved them, even if he didn't see them often. He would do anything to keep them safe.
Even lose himself.
"We only have one, I'm afraid," Krillen said apologetically as he returned, holding out the single, precious bean to the saiyan.
"Are you sure you don't need help?"
"Na, me and Vegeta can handle it." He was sure they could. They absolutely had to, it was essential, for the peace of the Earth, no, the universe.
"Alright, if you're sure…" Krillen trailed off, "Just…be careful, okay?"
"Yep, sure thing!"
As he raised his fingers to his forehead, Goku was memorising Krillen's face, wondering if it would be the last time he saw him as a friend.
Focusing on Vegeta's steady-tornado energy, Goku popped into existence in Bulma's living room.
"Just the one," he explained, handing it out for his companion to take.
Said friend was unusually solemn, regarding Goku with a warmth he had never seen directed at him with those eyes.
"Are you sure you want to do this?" Vegeta asked, trying one last time, but Goku wasn't about to back down.
"I'm sure."
"Very well, gentlemen. We'll depart now." Whis interrupted, "We won't be going far, though. The Darkness is spreading much faster than I anticipated."
And then they were away again, crossing through space in a tube of dazzling colours. The cylinder which they travelled in had never seemed as lonely as it did now, when Goku was contemplating his last moments as himself. There should have been more time, there should have been moments together with his family, his friends. But instead, he was with Beerus and Whis, who didn't seem to care about the saiyans, and Vegeta.
Well, that last one wasn't an issue for Goku, no matter what an outsider might think from watching them interact.
"Vegeta?" Goku broke out, needing to voice his mind in the short amount of time they had left. The question was important, very important, but somehow it seemed almost impertinent. A betrayal of trust.
"You'll look after them, won't you? Everyone. You'll protect them, right?"
Vegeta did not protest that he might survive this, because while the body might indeed survive, there was no guarantee about the person himself. Sensu beans could not heal a broken soul.
"I will," he replied, with more gravity then the special room his wife had built.
There was no more to say, after that. Goku wasn't one to talk about feelings, and Vegeta was even worse.
Beerus and Whis made no comments either.
Goku supposed the two of them had never really made an impact on the deities. They were just mortals; powerful, but still weak when compared to the gods. And they hadn't spent that long together either, when you considered how old Whis and Beerus must be.
When they landed on the planet, not that far from Earth in the scheme of things, the group maintained their silence. Goku took in the scenery around him with the air of one on route to the gallows. But also one who had made peace with it. He might have noticed the symbolic appearance of the planet on which they stood – there was no sign of life as far as their eyes could see. Not a hint of greenery, or even insects. Just solid rock, light grey like the cloudy heralds of rain.
Like a gigantic tombstone.
This would be it for him, his end. He walked away from the other three, mounting a crest and taking a deep draught of the blackened air.
He turned back to look at them.
His last teacher.
The enemy he'd failed to defeat.
And his rival turned…
Yes, he ought to admit, before he went, that Vegeta had become his best friend.
He wouldn't want to spend his last, crucial moments with anyone else.
"I guess, this is goodbye from me." He tried to keep it light, "Make sure I don't try to blow up Earth, okay?"
Vegeta only nodded at him, gazing at him steadily with those sad, sad eyes.
"Here goes."
Why was it that Kakarot was always making up for his failures? Frieza, Buu, Frieza again (and that still rankled) and now this.
He supposed this time it wasn't really his fault, but it felt like it ought to be. This was his duty, after all. For as long as he could remember, he had been the Warden.
Now Kakarot would be as well.
Would he be like him? Like he had been before Bulma's soothing presence descended into his directionless life?
Would he revel in destruction and carnage as a parasitic madness drove him to become more and more like the tormentor he so despised?
Would he care more for power than for anything that had once meant something to him?
Vegeta did not know. Kakarot did not have a saiyan's instincts, after all. He might turn out completely different.
He might not survive.
Vegeta gripped the sensu bean tightly in his gloved hand, gritting his teeth as he could only watch Kakarot take his stance.
Arms out, ready to start screaming.
And scream he did, determination emanating from every pore as his face scrunched up in concentration. Again, the ominous wind swirled around them, drawing the Darkness into Kakarot's waiting body. Vegeta forced himself to watch as a trickle of blood descended down the other saiyan's chin, as the tone of the screaming changed to one of agony.
The blackness surrounded Kakarot like a censor screen as the volume increased and the distinct tang of blood hit Vegeta's keen nose with full force.
The agonising cacophony formed a soundtrack to the images flowing freely through Vegeta's mind as he contemplating losing the only person he had ever considered a friend.
His goofy smile, his quintessential head-scratch, his woeful attempts at having a coherent thought process.
All that time they had spent together, as enemies, as rivals, as training companions and as friends. All those opponents they had fought together.
All those times Kakarot had surpassed him, only to need Vegeta to get beaten up to buy them time or some other such nonsense.
They had ended up spending a lot of time together, including three whole years with only each other for company.
Gosh, he was going to miss that big idiot.