when hazel was alive the first time, she fell in love with Sammy valdez. after she died, Sammy got married and had a child, and after his son یا daughter grew up, they had leo's mother. a while after leo was born, Sammy talked about how he had never forgptten hazel. after that, he passed away, I think. he felt responsible for hazel's death, btw. so basically Sammy is leo's great-grandfather. and hazel could have been leo's great-grandmother, if she hadn't died.
