Kinkaku/Genkaku were 2 brothers that didn't clash with each other! They were tight every time they had panel/screen time together.
I didn't vote because you left out Rikudou descendants Kinkaku/Genkaku
I gotta go with this. KinGin definitely seemed to be the closest brothers in this manga. I voted "Kumo Bros" instantly, but for me, that meant KinGin. lol
Most noticeable thing about them is how close they seem. All the other brother relations were strained, or the stereotypical trading barbs. I think it's nice how they're open in their relationship. When Ginkaku got in trouble, he felt no shame, and didn't hesitate, to call for his brother's help. And Kinkaku apparently is happy to give it. He flies into Bijuu rage mode when someone does hurt Ginkaku. Databook even states their bond gets stronger during an emergency.
And nice there's no rivalry that seems to go on. Seems both of them know Kinkaku is the stronger one. But Ginkaku is not jealous, and seems to rely a bit on his brother. And Kinkaku isn't a bully who tries to assert dominance over Ginkaku. They were an equal team who have nothing but love and respect for one another. Even though Kin was most-likely, known as the stronger and smarter of the two.
It's also cool having possible fraternal twins in the manga. KinGin would be the only ones. We had 3 sets of identical brothers. But KinGin, if not half-brothers, are fraternal twins. They look similar enough to be twins, which many assume they are, which some fraternal twins do. But their birthdays are 1 month apart, and their blood-types are different.
Kin = A, born March 7.
Gin = AB, born April 9.
Different hair colors
Both = 44
So not hard for me to think the simple answer is Kinkaku was just born 1 month early.
Because even in real life, twins have been known to have a gap in their births. Longest gap recorded is 80 days, so definitely not impossible in fiction. It could be that Ginkaku is a year older, and they died before he turned 45, but I can't buy the smaller, stupider, weaker, and more dependent, brother being the older one lol And Kishi followed their legend as close as he could. The original character, Gold Horn (Kinkaku) is the older brother. So fraternal twins or half-bros for me.