family

this section is filled with spoilers, so beware!

REAL FAMILY
You might have noticed the way Ellone talks of Raine and Laguna as Raine and Uncle Laguna instead of Mom and Dad.

Ellone's REAL parents died by the hand (or possibly minion's hands) of Adel, the feared sorceress of that time. No matter what the time, sorceresses have wanted Ellone's power to view the past, and Adel was no exception.

Raine must have adopted Ellone after that (how much after, I don't know), but she never forgot her parents.

MAKESHIFT FAMILY
Laguna
Remember uncle Laguna from Winhill?
Ellone and Laguna were really close when she was a child, most likely because her childhood was pretty chaotic and Uncle Laguna was a part of the 'normalitity'. And that the old guy just loves his little Ellone to pieces, so much so that he went and got lost on the way to Esthar and then got imprisoned and worked as a slave for a while trying to find her. That is some dedication. He is also the closest thing Ellone has to a father.
Find out more at Desperado

Raine
She's Ellone's mother figure, and had adopted Elle before Laguna came to the picture. Ellone always talked to her that she, Raine and Laguna should be all together (awww...). After Raine died, Ellone and Squall were sent to Edea's orphanage, because Laguna couldn't be found at the time.
More at Gentle Rain

Squall
Squall is the son of Raine and Laguna, so that sort of makes him Ellone's little brother. Squall always hogged Elle to himself in the orphanage, and was devastated when she left a couple of years later. That's the reason he doesn't really trust anyone. I don't know if anyone ever told Squall about his parents or if he just forgot because of Guardian Forces and such.
Find out more in Lost in Thought