Further summary: First and foremost, there will be spoilers. I will try to warn you, but I cannot promise I will be able to remember. Second, This plotline will not be linear, but rather snippets of times with the various teams. It vaguely follows the Fairy Tail arcs' timelines, but each arc does not correspond linearly. For example, the Avatar arc happens way later into the series, but in this world, the corresponding mission occurred before Lucy and Natsu even joined the FTG (Federal Territory Guard). This work will encompass all of the FTG, so focus may not always be on Team Natsu, but a majority will have at least one of its members.
The FTG, The Federal Territory Guard aka Fairy Tail Guild
Originally created by Mavis Vermillion, Precht, Makarov Dreyar, Wakaba Mine and Macao Dreybolt, the FTG was a revolutionary government agency that recruits at a young age to train and build. Chosen in their late teens and early adulthood, they are then given the opportunity to make a move into the available units.
Their services are given the highest honors upon leaving and the FTG is regarded as one of the highest positions of the government agencies.
The teams deal with serial offenders nationally and internationally, as well as terrorism. Though known outwardly as the Federal Territory Guard, it is known inwardly as the Fairy Tail Guild due to Mavis Vermillion's famous quote "Do fairies really have tails? Do they even exist... Like them, this place is an eternal mystery..." that was repeated by Makarov upon his promotion to Director.
In this world, there are various teams responsible for the working of the FTG. Below, I have listed the teams. I will also list down terms that are part of the BAU vernacular. If something comes up in a chapter that is not listed here, feel free to ask me!
Team A: Erza (team leader), Gray, Natsu, Lucy, Gajeel, Gildarts
Team B: Laxus (team leader), Cana, Freed, Bixlow, Evergreen
SWAT: Loke, Mirajane, Alzack, Bisca, Jet
Home Team: Porlyuscia (Medical Examiner, in-house medic), Wendy (in-house medic), Levy (tech specialist), Reedus (sketch artist), Droy (in-house forensics), Lisanna (trainer, former SWAT), Makarov (director), Juvia (director's assistant/right hand woman), Mest (assistant director)
Outside Forces Associated With FTG:
Retired: Wakaba, Macao, Mavis (semi-retired)
Army: Romeo, Laki
Marines (water-based army): Nab, Max
Other: Elfman (Navy SEAL), Warren (NSA), Precht (mole)
Dead: Rob, Zeref
At the present time, Team A has been together for a year. There will be chapters previous to that year, so characters will be missing from the team. For example, one-and-a-half years before the present time, the team consisted of Erza, Gray, Gildarts, Makarov and Mavis. Mavis semi-retired, and Natsu joined the team as their newest member. That means stories that occur longer ago than one-and-a-half years would not have Natsu in them.
Present time is X777. This does not have any significance to the team, like it does to the Dragon slayers in the Fairy Tail actual universe.
BAU Vernacular:
Victimology: the study of the victims of a crime, patterns in the victims (ie, all brown-haired, all philosophy majors at specific university)
Go-bag: a bag that all field agents have at their desk that carries toiletries and clothes if they have to leave immediately (not a gym bag)
Behavioral evidence: evidence at a crime scene that is left due to behavior, usually not physical (ie, having to straighten out all the books on a table)
Criminal Profiling: uses observations at the crime scene, victimology, and the pattern of crimes to narrow down a suspect list
Kevlar vest: vest that protects agents from bullets when they go out in the field (technically bullet-resistant, not bullet-proof)
MO: modus operandi, the way they carry out the offense
Signature: something unique to the "villain" left at the scene (ie, a playing card, a certain song lyric, piece of a poem, etc)
UNSUB: unknown subject, the name used to describe the "villain" when their name is not known
And that concludes that...Now, on, to the show!