The siblings looked after each other unlike their Great Mafia King, family man, father Vito
among others -
Sonny- Sonny as acting Don foresaw the family's future, bankrolled the casino/hotel and sent Fredo over to “learn the casino business” having arranged Fredo's protection with the Molinari family
- Sonny was forced to get involved in his sister Connie's domestic violence and ended up losing his life because of their family man father Vito's inaction
Fredo- What a welcome party! Fredo had organised for Michael in his territory
- Fredo is the only one who congratulated Marine Michael and got his hand nearly broken! by Sonny
Michael- Michael always taken care of Fredo
- Michael invited Connie to live on the Tahoe estate with her kids that Connie won't be deprived of anything and Connie can have everything she wants
Connie - Connie moved into the Tahoe estate after Mama's death, to take care of Michael
- I believe Fredo’s “drowning” was something Connie self-invented, to obscure the truth of the horror of her brother Michael killing another brother Fredo and also as comfort and support for tormented Michael