Dino is the current and tenth head of his family, having inherited the position from his father. He cares deeply for his subordinates, to the extent that he becomes much more clumsy in their absence. They feel the same affection for him and sometimes tease him but remain devotedly loyal to him. Most notably, he is accompanied everywhere by a select few underlings, especially his trusted right-hand man Romario.
Dino calls Tsuna his "cute little brother", and in return Tsuna respects and admires him as an older brother figure. They have somewhat similar personalities and bond easily over their shared experience of having Reborn as a tutor. Their first meeting was slightly awkward, because Dino teased Tsuna by saying that Tsuna didn't seem impressive, though he did later apologize for this remark. They have since bonded through many activities and battles.
Dino and Squalo were schoolmates when they were about Tsuna's age. They first met when Dino caught a bloodied Squalo climbing over one of the school walls and offered to treat Squalo's wound. Though this offer was rebuffed, the two were at the very least familiar with each other by the time they reunited eight years later. Dino also cares enough for Squalo to rescue the latter from being eaten by a shark, and they talked openly during Squalo's hospitalization. Squalo felt that Dino should have just let him die, but Dino disagreed. In the future, their relationship has considerably improved and Squalo leans on Dino for support when returning to the battlefield. However, in the last arc, Dino's status as Hibari's teacher and Squalo's loyalty to Xanxus resulted in some renewed tension; Dino claimed that Hibari would have no problem defeating Xanxus and Squalo was visibly annoyed by this. Squalo was also angered by Dino's attempt to antagonize Xanxus. While staying at a hotel, Squalo behaved a bit more casually towards him and remarked that it would be nice to have a quiet meal. In the alternate future, Squalo got a gift for Dino in the form of a large tuna after taking a boat to Japan.
Reborn's lessons were no easy task. There were many times I'd thought I'd die.
Reborn is Dino's former tutor and occasionally still refers to Dino as his loser student. In Haru's interview segment, Reborn was annoyed with both Dino and Tsuna. Despite the Arcobaleno's sadistic nature, however, Dino still wanted to learn more from him and credits him with making Dino into a capable boss. Dino and Reborn are not quite as close as Tsuna and Reborn.
Bianchi tried to kill Dino when he was still being taught by Reborn. In the future, he addressed her by her mafia nickname, "Poison Scorpion", and entrusted her with the younger girls.
Dino respects Timoteo as the head of the Vongola, whom the Cavallone are firmly allied with. And they share a good relationship, Dino having known Timoteo since he was little and sometimes asked to do things that Timoteo can't task his subordinates with. But there is one instance of rebellion on Dino's part: When the Ninth wanted to test Gokudera's loyalty, he wanted Dino to execute Gokudera if Gokudera tried to go to leave Tsuna for a supposed promotion. Dino decided he would hide Gokudera instead. Apart from this, it is likely that they often meet for discussions and maintaining their Families' alliance.
After Gokudera passed Timoteo's loyalty test, Yamamoto ended up going to Italy instead and was hosted by Dino.
In the Future Arc, Dino noted Yamamoto's cheerful demeanor despite their rather dire circumstances and reflected that it wasn't surprising. He seemed to know Yamamoto well enough and was familiar enough with Yamamoto's idiosyncrasies that such an attitude only amused him.