Well my hypothesis that Igneel might have been Erza's father can be disregarded just as fast as I came up with it last week xd
It's still unclear though whether Erza is now an unexpected side effect of the dragon magic on Irene or that she became pregnant the normal way. It's good to see though that my analysis of dragon slaying magic was correct; that it in fact is normal dragon magic used/applied by humans and that the term "dragon-slaying magic" is nothing more than a subjective formulation.
So 99% of all the guys that were send to the future just coincidencely met in the same guild?
It's not that much of a coincidence. It's still a bit pushing it, but in the end there are some determining factors here. For starters we can actually calculate the exact percentage considering there are, counting Erza, 6 persons who supposedly were sent from the past to the future: Natsu, Gajeel, Wendy, Erza, Sting and Rogue. The two latter are not in FT, so that makes around 66,7% of the people who came from the past eventually joined FT.
Secondly all of these already formed a group 400 years ago. Well Erza is still uncertain, but all the dragon slayers already knew each other and they were all from Ishgar. With exception of Erza, all of them were also already mages when they made the time jump. So that their geographical spread wouldn't be that great, is rather logical and so is the fact that they most likely would join a guild as that's a logical course of action for a young mage. In the end not all of them originally joined the same guild. The six of them were spread over four different guilds and only after Gajeel and Wendy's original guilds were disbanded, they joined FT. Which was at the time also not that odd considering FT was one of the most popular and prominent guilds in the region and in particular Wendy had friendly ties with them.
So in regards to all the Dragon Slayers, that this exact scenario would unfold, wasn't that unlikely as it seemed. The only one that doesn't fit the pattern, is Erza. She joined FT because of her relationship with Rob and even now it doesn't seem she had any direct connection with the dragon slayers and their mission. So yeah that was kinda "coincidental" that she of all people also ended up in FT, but that does not really apply to the others.
