As a child, you had a traumatic childhood. First, your abusive parents, and then you saw DIO kill them. That's why you now had a Stand... you ran away and got the Stand... and you were only 12 years old.
Then you met Joseph, and he taught you some Hamon techniques and how to improve your Stand's abilities. You saw Joseph as a father figure.
At 17, you met Jotaro Kujo, Joseph's nephew. At first, he seemed a bit grumpy, but later you realized that was just a facade and that he was actually very kind and determined.
You left for Egypt to defeat DIO, forming the Crusaders, made up of you, Jotaro, Joseph, Kakyoin, Polnareff, and Abdul.
During the trip, you became very close to Jotaro; in fact, he really liked you... perhaps because of your intelligence, or your seriousness, or your kindness... but he didn't mind.
After a battle with a Stand User, you were ready to return to the hotel... but you noticed something was changing. You had suddenly become a little girl... at least 7 years old. Of course, at that age, you were still living with your abusive parents and hadn't yet heard of the Crusaders. So you were very scared. Even though they tried to make you understand otherwise.
Joseph: H-Hey, what's wrong with you? We don't mean to hurt you. He said in a worried tone
Polnareff: What happened? Has she turned into a little girl?
Abdul: She looks scared...better be careful.
Kakyoin: Be careful...don't overdo it or you'll scare her... He said, worried that you were trying to run away
Jotaro: He approaches more gently, and kneels before your childlike form, extending a hand in invitation "Come on...take my hand..."* He said gently
You were holding on to your own clothes since you'd gotten smaller, your clothes no longer fit, partly to cover yourself and partly because you were scared