In Part 1, Jonathan protected a kid called Poco and his Cool Big Sis from Dio’s Mooks.
At the beginning of Part 2, we're introduced to Joseph displaying this to a young African American boy named Smokey Brown, when he saves him from two racist cops and defends him publicly from an ill-mannered thug who insulted him. Smokey ends up becoming an ally of the group during their fight against the Pillar Men.
In Part 3, Jean-Pierre Polnareff's motivation for joining the protagonists is to track down the "man with Two Right Hands" who raped and killed his younger sister and avenge her. He succeeds in his quest, and sticks with the group for the rest of the part.
Once again in Part 3, protagonist Jotaro protects Tag Along Kid Ann multiple times.
In Part 4, Josuke and Okuyasu developed this for middle schooler Shigekiyo "Shigechi" Yanguu. Despite Shigechi's greed annoying them to no end, and giving them a lot of trouble with his Stand prior, Josuke explains he and Okuyasu felt they couldn't leave him alone and befriended him. Once Shigechi meets his tragic end by Yoshikage Kira's hand, Josuke and Okuyasu become motivated to track Kira down and bring the villain to justice.
Also from Part 4, Reimi Sugimoto had a big sister instinct towards young Rohan. She sacrificed her life to protect him from Kira when the serial killer first got started.
Although Keicho Nijimura, the first arc villain after Angelo, works mostly as a deconstruction of the Big Brother archtype, he does meet his end saving Okuyasu's life.
In Part 5, Narancia develops this towards Trish after her father, the Boss, tried to kill her. While Giorno, Mista, and Abbacchio all choose to protect her over their loyalty to Bucciarati, Narancia is particularly determined to protect her.
During the events of Part 6, the entire group has this to a certian degree towards Emporio Alniño, with Jolyne being the biggest example. Her last moments during Made in Heaven is to tie Emporio to a dolphin and send him to safety while she holds off Pucci at the cost of her life.
