This Idea is that the Fairy Tail Guild Master uses a hidden portal to go a different world for a few days to get away from the insanity of his guild. While there he finds a 4 year-old boy being left at a train station by his father while being told he is useless. Makarov takes offense at this and offers the boy a new home with people who won't leave him for such a stupid reason, the child accepts and so Shinji Ikari changes the fate of himself and his world in true Fairy Tail style (forge your path and who cares what others say). Gendo, there is no word in the English or Japanese languages for how screwed you truly are. (Paraphrase of a quote from Shinji and Warhammer 40k summary, one of the best written and most original fics ever.)
1. First he has to return to his world in time to receive the letter calling him to Tokyo-3 at the age of 14
2. He can learn any style of magic other than dark magic
3. No god like Shinji, powerful yes, but FARIY TAIL powerful, meaning mass destruction in his battles while still being able to be beaten and sometimes having to snag victory form the jaws of defeat.
4. The time line must be set up to make Shinji the same age as Wendy.
5. Allowed pairings: Shinji and Wendy, Shinji and Askuka, Shinji and Rei, Shinji and Hikari, Shinji and Mana, and Misato and Kanji. Everyone else, your choice who they end up with as long as there is no male + male pairings
6. Tasteful bashing is allowed, over the top is not
7. Shinji is and must remain a member of Fairy Tail
8. He is allowed to be in any of Fairy Tail's canon events as long as he goes through the NGE story line at 14.
9. some people prefer for Shinji to ratain some of his canon personlity in fanfics a good way to allow him to have a some of the traits is to have shinji start to view Lisanna as a older sister/mother figure so that when she disappears Shinji will have a reason to develop some of the issues he has in in the real series.
As one would say in French
Gendō, vous sont vissés
Online translator, So don't flame me if i got the translation wrong