soulofaginger

Giotto

G has known Giotto since he was about eight, they grew up together as best friends and a century being sealed away in a ring hasn't changed that a single bit. G adores Giotto and sees him like real family. Giotto was the one who more or less pushed G in a direction where he could do something good with himself rather than ending up a thug, and for that G has always been grateful. They also balance each other out well. G is good at picking out the times when Giotto overworks himself, and bringing him down and reminding him of their humble beginning in the Vongola... typically through drinking with him and harassing him with childish pranks like he did when they were children. In turn, Giotto is almost a kind of go-between when it comes to people and G, as G often gets confused by the logic of normal social behavior. Giotto also gives G a purpose, something to do with himself, which, in a place like this, is what keeps him pushing forward.
Giotto also has a saint-like patience with G, as G is overprotective and prone to being clingy. Much to G's irritation, Giotto typically handles this by strategically "losing" G wandering away at opportune moments.
In Maison, G has caught up a bit with events from after his death, and while it pains him to know he missed out on seeing his best friend get married and start a family, he's glad that maybe his sacrifice bought Giotto a few years to spend with them. It also has kind of spawned a bit of a switch in G's typical 'I hate children' mentality, and he's started 'collecting' a few of them. After all, if Giotto did it, it's obviously something great!

Hayato Gokudera

Given that the last thing G remembers from back home was his ring breaking, G was ready to deck the kid when he first met him in person. Naturally they got off to a rocky start, if Giotto hadn't been there to play mediator and keep both of them relatively calm, things probably would have gone worse. Thankfully this lead to the discovery that Hayato had no recollection of the ring breaking, revealing that he was from an earlier time and G didn't see much of a reason to scold him for something he didn't know about yet. Which is when they kind of almost started to treat like civil human beings (read: they started harassing each other for fun). After picking up so many similarities between himself and the boy he took a bit of a shine to him, and decided to help ready him for his aspiring position of right-hand man. While G wouldn't admit it to save his life, he really enjoyed the kid's company, and watching the positive effect of the boy's training and his growing confidence gave him an odd sense of pride.
After a bad run-in with the Doctor or the house, Hayato stayed by G's side and tended to him the best he could, despite seeing his predecessor in such a state was hard on him. Even through his weakness and fading in and out of consciousness he did what he could to encourage Hayato and walk him through it, while Hayato did his best to do the same for G. While in this weakened state, G verbally admitted his fondness for Hayato and father-like protectiveness over him. Once G was more conscious, Hayato questioned him about it and the conversation ended with G claiming Hayato as his own kid.
They've had their petty arguments and such, as they don't always see eye-to-eye on most things. Again, G would cut out his tongue before admitting that he is somewhat afraid of the situation. G knows what he's good at, and is wary of new things, and dealing with other people doesn't come naturally to him. Even if Hayato and he think very similarly, he worries that he'll botch things up and end up damaging Hayato more than helping him.