1(Katekyo Hitman Reborn)

An Au where Nana is Skull's daughter, when he had gone to join the Arcobalenos was with the promise from Kawahira that Nana would be protected as she had waken as a misty sky when her mother had died when she was pretty young.

Skull had known about the mafia before he joined the Arcobalenos as it was a mafioso who tried to force him to bond with him and killed his best friend(who was also Nana's mother, Nana was born from one drunken night but she is loved by both of her parents) but he kept distance from them so he or his daughter wouldn't be used for whatever they wanted.

Kawahira had Nana move to Namimori where many ex-mafiosos and similar went to after being betrayed or didn't wish to continue being a mafioso so the amount of people with flames there would hide hers but took Skull to visit her every week even after the curse(Skull thought that Kawahira and Checker Face were two different people and that Kawahira was unfortunately someone forced to work with Checker Face so he trusted him to take care of Nana who saw Kawahira as a uncle/grandparent figure).

During the years Nana met Iemitsu, married and had Tsuna both Kawahira and Skull were unable to visit her for some happening in the mafia world and could only communicate by letters were Nana never mentioned Iemitsu's name.

It was only after Tsuna was sealed that the two were able to visit Nana and were furious when they noticed someone sealed Tsuna and seemed to have forcefully bonded with Nana's mist flames(if the bonding was by accident from Iemitsu's part is up to the writer).

The forced bond changed Nana to the oblivious person in canon and neither could accept that the girl they, technically, raised together had become that and how Tsuna would suffer because of the seal so Kawahira actived a barrier in Namimori that didn't permit anyone to enter unless he or someone in a high position in Namimori gave them permission(every mafioso who started actually living in Namimori, not like Iemitsu did, was told about a barrier existing that was left behind by some ancestor to protect those living there and that once the barrier was actived everyone even those with no flames would feel it and know someone had hurt one of them).

It didn't take long for people to realized that it had been the Sawadas the reason behind the barrier's activation as they had been the only ones who had guests recently so slowly everyone started visiting them and helping them(those with flames were instructed to help slowly break the seal in Tsuna and try to find the elements for Nana's sky flames to break the hold her 'sky' had on her while those who didn't have them were explained about the flames and helped with whatever they could like keeping Tsuna safe from how the seal made him clumsy which would end with him hurt).

By the time Reborn was called to train Tsuna the barrier was down but the people from Namimori were still protective of Nana and Tsuna like the two were of the other residents besides Skull and Kawahira had made sure that no Arcobaleno could know that Skull was in Namimori and that he is Nana's father.

Reborn and the others won't have a easy time getting what they want from Tsuna(maybe Tsuna got his full element in Namimori? It could be ocs or in place of those from Italy it could be Kyoko, Haru, Mochida, Hana, etc?).

The ships, if Iemitsu will be forgive, if Kawahira came clean to Skull and they are looking for a way to make sure there is no new generation of Arcobalenos, etc is up to the writer.