"So, you were looking for my marble, when you were attacked by a bandit, then kidnapped by a dinosaur?" Kakarot summarized what Bulma had told him, holding the Dragon Ball, which he'd pulled out of his capsule at Bulma's request, in the palm of his hand.
"Exactly! I'm trying to gather all seven. I already have two, and I know where a third is, so I just need the other four. And they're called 'Dragon Balls', kid. They're more than just marbles. So, can I have yours?" Bulma asked, reaching for Kakarot's Dragon Ball without even finishing her sentence.
"No way! My master gave this to me! It's important to me, you can't have it." Kakarot explained, pulling the Dragon Ball back before Bulma could take it. "And my name is Kakarot."
"Bulma." She extended her hand for a shake, but Kakarot just looked at the hand warily, clutching the Dragon Ball in his grip, "I'll pay you for it! Everyone needs money, right? I'll give you a lot for that Dragon Ball of yours. Promise."
"No way! My master gave me this Dragon Ball. I won't let it go for a million, billion zeni!" The boy declared, "But…"
Bulma's developed business sense could tell it'd found a potential opening. Like a shark, she jumped on it. "But what?"
"My master had one of these. My grandpa does, too, and so do you." Kakarot's brain worked overtime, making the connections in his mind as he stared at the Three Star Dragon Ball in his hand.
"Yeah, so?" Bulma asked. While she was grateful to the boy for saving her, and obviously knew that, as a tailed Saiyan, Kakarot was no ordinary child, she also knew from Zeck that most Saiyans were straightforward, even a bit dull, but stubborn like Tater.
From what she'd heard, making a deal with a solo Saiyan child was like pulling teeth.
"My master and grandpa are really, really strong." He explained, "Like… really strong. And you…" He trailed off.
"What about me?" Sensing that Kakarot was about to say something insulting, Bulma put her hands on her hips in a defensive pose.
Knowing from experience that it was very stupid to insult a woman, Kakarot chose his words carefully. "...It's… not normal… to get… attacked, twice at once, you know?"
Kakarot was proud of himself for navigating that minefield so carefully. He'd managed to get his point across without specifically calling Bulma accident prone.
He was proud of himself. For about five seconds.
"Are you calling me accident prone?!" She accused angrily.
"...Sorry, but you kind of have to admit… I think these 'Dragon Ball' things attract trouble, or at least strong people. " He replied, scratching the back of his neck.
"And you're a Saiyan… so you like trouble." Bulma instantly connected the dots.
"You know about Saiyans?!" Kakarot's eyes went wide. He knew as well as anyone that the idea of super-powerful aliens with monkey tails weren't exactly common knowledge.
"Of course, I know everything!" Bulma boasted, "How about this? All I want to do is gather all seven Dragon Balls and make one wish. That's the reward for gathering them, apparently. How about you act as my bodyguard and help me gather them? I get my wish, you get your excitement?"
What Bulma knew about the Dragon Balls was limited to what Zeck had told her.
In other words, what the other Saiyans had learned from their time on Namek. Tarble didn't like talking about the Dragon Balls because he didn't like the idea of using them unless someone needed to be revived from the dead by Shenron's power.
Anyways, according to what the Namekians had relayed to the four Saiyans, once all seven Dragon Balls were gathered, one simply needed to call on the Eternal Dragon in the planet's native tongue, and he'd come out to grant three wishes.
According to Earth legend, Earth's Eternal Dragon was named Shenron.
And that's all Bulma really knew about it, besides that vague warning Tarble'd given about negative energy and the planet's core or something. She didn't know about the fact that Earth's dragon only gave one wish, she didn't know about Kami, the planet's guardian who'd created the Dragon Balls long ago, and she didn't know that the balls would turn to stone for a year following the wish.
So, in Bulma's mind, the idea was simple. Make the wish, then give Kakarot his Dragon Ball back.
Fortunately for her, she didn't know any better than that.
"Okay. I'll help you gather these things. I'll protect you, do all of the fighting, and you can have your wish, Bulma." Kakarot decided with a nod.
"It'll be nice working with you, Kakarot. But you might not get too much action. I'm really not as accident-prone as you seem to think." Bulma told him.
Kakarot arched an eyebrow. "You know, I have a feeling that I won't have a problem, Bulma."
"Great! Well, I'll just hold onto that-" Bulma reached for the dragon ball, but it vanished like lightning, only to appear behind him as the young Saiyan started juggling it with his tail.
"Nice try." The young Saiyan smirked, catching the ball with his off hand and pocketing it. "Sorry, but my dragon ball doesn't leave my hands until you need it."
"...Fine." Bulma pursed her lips, annoyed.