Background: His father had an extremely strong sense of Justice and was disgusted with the violence and corruption that was occurring everywhere. So he started a Vigilante Group to protect those who had no other protection. He named this group Vongola (clam) Protection Agency.
Tsuna was raised by his father
Giotto alone for all his life. At the age of 5 he started attending Serenity's school and was enrolled in Kazuma's boxing/self defense classes. He remained there for 5 years, meeting Alice while there.
At the age of 10 Tsuna's father removed him from Serenity's school to take a more active roll in Tsuna's education, raising the boy to be more like him and to gain the knowledge needed to become a successful leader of the family business. Tsuna still attended classes at Kazuma's but they became more and more infrequent.
From the age of 10 to 14, Tsuna learned everything about Vongola and his father's ways of running things. He met all of his Father's contacts and even made some allies of his own. It was during this time that he met Artemis Fowl, Haru and Euphie among others.
Everything was going well for Giotto and Tsuna until one day, Giotto was betrayed and literally stabbed in the back by one of his closest followers.
Tsuna is now in charge of his father's business of protecting everyone who needs it and fighting against the gangs when they get out of hand. Despite being the tender age of 14.
CR
Allies:
Jigen: friends with Tsuna's dad and returns to work for Tsuna when he hears of Father's death
Train Heartnet: wandered in one day hungry and Tsuna's dad fed him and offered him a job.
Artemis Fowl: Tsuna's father saved his life one day and brought Artemis home with him. Tsuna and Artemis are like brother and Tsuna works hard to protect him. In exchange Artemis provides financial support and is an inventor for Vongola
Zidane: freelancer that works with Tsuna, providing him with information and occasionally backing him up in a fight.
Javert: once friends with Tsuna's father, he now works with Tsuna. Their connection is secret and will remain that way. Tsuna looks to Javert for help with difficult problems in running Vongola
Miles Edgeworth: Share a common goal of ridding the government of corruption. not sure at this point their full connection. But they have worked together in the past.
Serenity: He attended her school for a few years until his father took him out to "train him in the family business". He receives financial support from her for Vongola in order to better protect people. I'm thinking he sees her as a mother-type figure and probably has talked with her about his grief over his Father's murder.
Aeris: An informant for the Vongola
Luffy: Runs a gang that is one of Tsuna's allies. They help each other out sometimes and are just friends in general.
Haru: Haru is an upperclass citizen. One day while out patrolling/training with his father, Tsuna sees her being robbed and defeats the robber. Because of this, Haru was smitten by her rescuer and eventually they wind up dating. She's been a huge support to him since his father's murder.
Mulan: After being kicked out of the Army she joins Tsuna's organization.
Jade: allies for sure, possibly have a sibling-type relationship. TBD
Fuuma Sakurazuka: allies (still plotting)
Ishikawa Goemon: ally, still working out details.
The Doctor: Family doctor after tsuna's father died.
Tifa: Ally. Informant/sometimes fighter. possibly. TBD but those are our ideas.
Garnet: A while back, Garnet got into trouble and Tsuna (and dad) where there to save her. They would have told her that if she ever needed help of any kind, a friendly face to talk to, or just protection to come to them. And then told her where to find them.
Now that she's run away from home, she's taken Tsuna up on that offer and come to him. Looking for help (and possibly some protection) now that she's "on her own".
Kazuma Sohma: Tsuna trained under Kazuma for a few years until his father decided to take a more active role in his education and removed him from the school. However, Tsuna remained friends with Kazuma and has shown up to protect him from Anti-Japanese groups and (possibly) some mafia trouble. He also frequents the store when he gets a chance and has asked Kazuma to keep his ears and eyes open for information.
Jean Valjean: Father of Alice. He and Tsuna know each other and Valjean supports tsuna's organization. including with monetary support.
Franziska: possibly knows Tsuna because of Edgeworth. Not sure yet.
Namine: went to school with Tsuna. possibly knows about the protection agency.
Kyouko: I think she works with Tsuna? not 100% sure. but she's connected to the agency.
Seiji: In-office medical technician. Deal with minor injuries and calls The Doctor up if anything major comes up.
Enemies:
Hades: They've had several clashes over protecting people and Tsuna entering Hades' territory.
Lelouch: TBD. probably had clashes.
James Hunter: rouge gov worker. relationship TDB. Had clashes with Tsuna in the past. Tsuna possibly working towards trying to detain him.
People to protect:
Noel: Tsuna has shown up to protect her a few times. She denies needing his help and refuses to join him. but he still will help her out if he gets word in time.
Euphemia: still plotting. Tsuna protected her one day when she had snuck out. She now goes to him whenever she sneaks out for protection. Tsuna views her as a Big sister type figure. which makes him all the more protective of her.
Gwendolen Chant: Tsuna protected her at one point. Even though she didn't really need it.
Alice Valjean/Liddel: They attended the same school and became friends there. Tsuna met her in the auditorium with the intention of providing her with protection and showing her around school. They became friends and remain so despite Tsuna having left the school
Will be edited and such. Just wanted to post this.