...the cursed infants
The Arcobaleno (it: Rainbow), is the group of the strange infants, who are recognised by wearing rainbow-colored pacifiers. The color that they got is the color of their own dying will flame. When they are near each other, or simply in the same area, their pacifiers will glow to tell that there is another arcobaleno member in the area.
Thanks to Lal Mirch's flashback (in the chapter 179) we know, that these infants once were adults, that decided to take a curse on themselfs to protect the Tri-ni-set(7³) or Ultimate Power. Each of them has a curse and specific abilities, besides the fact that they can emit the dying will flame throughout their body (an example is during the fight between Lal Mirch and Millefiore general).
There is not much know about them, but thankfully to a picture on Akamru Jump (got on 2chan, thanks to Nekoi), that has all of the Arcobalenos in adult form too, we know the identities of all 7 main members of Arcobaleno.
Colonello is the holder of the Blue pacifier, he wasn't planed to be one of the seven, he decided to take the place of Lal Mirch, who was his trainer, even if he didn't want her to change in to an infant, that didn't happen, actually he made it worse. He is the one who is in charge ov the Magia Land, and in the past was member of COMSUBIN, and that makes that he uses havy artillery, like anti-tank rifle, which is his primary weapon. His pet is an eagle, who is mostly on top of his head, and because of that, he has the ability to fly, even to distant places. He sees Reborn as rival (and so does Reborn), but actualy they are quite alike - being a tutor, falling asleep sudenly, and shapr tongue. He is chosen as Ryohei's tutor, to prepare him for the Vongola Tournament, and in the future it seems he dies, protecting Viper.
Verde is the one who has the Green pacifier. He was mentioned by Reborn, who said that he sent assasins to kill Tsuna. It's said that Verde main power is camuflage and invisibility. He made suits for his subordinates to make them invisible, but he made them the way, so the children could see them, afraid some of them could actually try to kill him. It also apears that he is one fo the three scientists who developed the Box weapons, and it's said that in the future arc he is dead.
Skull, the owner of the purple pacifier. It's impled that he isn't really powerfull, or at least Colonello and Reborn continue to bully him, and Reborn has saw him always as only an errand-boy. He normaly dresses in leather outfit and a motoclycle helmet, the same are his subordinates from Clacassa Famila. His animal is a giant octopus whose tentacles follow his hand and fingers moviments. It's said that he is dead in the future.
Viper is the one who has the indigo pacifier. She/He is part of the Varia, under the name Mammon. She/He is the spellcaster and has the abilities to cast illusions, and also a weird power of sneezing - she/he is able to locate people if he sneezes on a paper the spit shows the way to the searched person. Her/His pet is a frog named Fantasma that is usualy on his had. It can turn in a yellow salamandre and bit it's tale, forming itself as a halo above Viper's head and it gives him the ability to fly in combat. She/He is also the one who is trying to break the Arcobaleno curse, and he managed to seal her/his own pacifier so that the other pacifiers can't sense her/him when near. During the Varia arc, she/he is able to defeat Chrome, but she/he isn't able to do the same, when Mukuro takes over the girl's body, and she/he is defeted. In the future it's said that she/he was saved by Colonello, but is also clamed to be dead after comiting suicide. I use she/he, because I'm still trying to figure if Viper is a male or Female.
Luce is the carier of the orange pacifier. She was the boss of the Giglio Nero - that is black part of Millefiore (because Byakuran convinced Uni to join him, as the attack part of the organisation). Besides being the boss, she is also the mother to Uni. She was quite friend with Gemma, and he was really loyal to her. Why she died and how she died is not know, but we know that her doughter took her place as a boss of the family. Her animal is a squirrel.
is the one that has the red pacifier. And the little
we know about him is the fact that he is I-Pin's master, he is Chinese and he
in his adult form looks like Hibari. As animal companion he has a monkey.
Lal Mirch should have been the holder of the Blu pacifier, but Colonello took her place, and so she is the holder of the corrupted pacifier. She is the only half mamber of the Arcobaleno, even if she states she is not worth making part of it. She is part of CEDEF, along with Tsuna's father Iemitsu and they work for Vongola 9th. She is a crucial character in the future arc, because she helps also to train Tsuna for the invasion of the Melone Base. She helps them along the path, but she is knocked out, after she won defeating a Millefiore general.