Varia headcanons, because they're far less likely to get lost here than in my thousand of pages of notes!
The Varia have an incredibly complicated organisation system that includes people reporting back to Officers who then report to Xanxus. The Officers are traditionally the strongest of each Flame type, but since Xanxus is a Sky most Officers are his Guardians.
There is a non-Flame division. They mostly rule themselves, but report back to Xanxus. They take on most of the jobs that require little-to-no use of Flames, or deal with non-Flame society.
Coming back to that complicated organisations system- there’s two types of members of the Varia- Named or Nameless. A member acquires a Name when they complete their first job. From there, they can choose to work as a solo or duo under their Flame type, or in a squad under the leaders Flame type. (Squads have themed Names and a member is expected to change their Name is they join a squad)
There aren’t meant to be women in the Varia. It wasn't a rule put in place to be sexist, but rather to deter heiresses for joining, so that the Varia didn't have to deal with Dons wanting their daughters back to play alliance bride once they were Named. There isn’t an ‘official’ work around for this rule, but there is an unofficial ‘see something, say nothing’ rule in place in regards to gender. (There's also an unofficial rule about not mentioning that someone left at the same time an heiress returned to a Family to get married, only for the happy couple to die right before the Varia member gets back from ‘vacation’)
Character-specific headcanons
Squalo is a Cloudy Rain. He has a habit of taking off and vanishing from sight when he feels like it. Pre-Varia, he would hide in Xanxus’ rooms, or find some obscure hiding place. It’s why people weren’t too worried when he took off on a world tour that ended with him losing a hand and gaining control of the Varia. (When Xanxus is in the ice, Squalo sits by him. He falls asleep to the sight of Xanxus, frozen mid-snarl, more times than he can count)
Lussuria is actually ace! The whole necrophilia thing happened because the guy they were set to kill as their ‘entry-level job’ ended up in a kink club, unguarded and alone, and they took the shot. Still, to take a Name there has to be proof that the job was completed. So they bought the body back with them to Varia HQ, still clad in only a gimp mask and leather thong- how were they to know that the head or heart of the guy was sufficient proof? (Their original Name was something more obvious, and a reference to the assumptions people made when the bought the body back. When they harmonised with Xanxus, they figured they should keep with the ongoing themes- Sins (for Xanxus’ set) and odd sexual tastes(from their own Name). So they took the name Lussuria, meaning ‘Lust’)(They let the assumption continue because they get far less people acting interested in them if everyone thinks they have eccentric tastes)
Up until the ice, Xanxus had grey eyes. Zero point ice (first edition, at least) is fuelled by the Flames of whoever is trapped inside the ice, which means that for eight years, Xanxus was constantly putting out Flames. It became second nature, and he can’t exactly stop it. His eyes glow red because of this constant output.
Talking of Xanxus, the name Xanxus is Aztec, meaning ‘protector of god’. However, looking at the etymology of the name, it could also be derived from the Greek name Xanthos, meaning ‘golden-haired’, or just ‘gold’. It’s also said that Xanthos was used as an alternate name for the god Apollo. (I find it ironic that the leader of a group of people named for the seven deadly sins has a name meaning ‘protector of god’)