Fairy Tail chapter 514 spoilers provide interesting details about the origin of Dragons, their interaction with humans and most importantly, Irene Belseroin's life hundreds of years before she becomes a member of the Spriggan 12.
Dragons and Human Co-exists:
Dragons once co-existed with humans in a kingdom in Ishgar. In Dragnov Kingdom, humans freely interact with Dragons without any fear the scaled monsters would eat them or raid their villages.
However, a threat started to emerge from the West. News of dragons eating up people and destroying human civilizations was starting to spread across Ishgar. These dragons are apparently heading to Ishgar very soon, something that alarms both human and Dragons living peacefully in Dragnov Kingdom.
The Power of the Dragon-Slayer:
Irene also explains the power of the Dragon Slayer magic. Dragons grant humans the ability to kill Dragons with evil intentions and that's Dragon Slayer magic. Unfortunately, the individual who accepts such gift must also face the inevitable truth of becoming a full-fledged Dragon, which is the last stage of being a Dragon Slayer.
Erza and Irene Connection:
Irene then tells Erza that she was about to reach the point of becoming a Dragon at the time of her pregnancy. The forbidden past of daughter and mother will be explored further in the next chapter: I am you, You are me! The secret of Erza's birth is beyond space and time..!!
Information for Chapter 515:
Jump Weekly Shone will be taking a break next week, moving the release of Fairy Tail chapter 515 to December 28. The Alvarez Empire saga is getting more and more intriguing with Irene's revelation that she's the mother of Erza. Then, there's the evolution of Natsu and Lucy's relationship, Mavis' role in the war, and Zeref's determination to complete his mission of slaying Acnologia.