Fairy Tail: Final Series

Synopsis

Mavis telepathically orders Gray, Lucy, and Happy to rendezvous with her as part of her strategy against Zeref. The three leave Natsu as he continues fighting Zeref, who grows increasingly violent and bloodthirsty under the influence of his curse. Larcade attempts to assist Zeref in killing Natsu, but Zeref angrily attacks Larcade for interfering and denounces him as his son, revealing Larcade to be an Etherious he created. Meanwhile, August continues to question Gildarts and Cana's relationship as he withstands their attacks. After watching him dodge Cana's magical cards, Gildarts discovers that August is vulnerable to tool-based magic, and uses a spell with his own prosthetic arm to injure him. In a series of flashbacks, Zeref and Mavis's son is born and abandoned by Precht while Mavis is in stasis. Imbued with knowledge of his parents' identities, the son grows up and eventually encounters Zeref; unaware of his son's identity, Zeref notices his resemblance to Mavis and names him after the month he shared a cherished period of time with her, revealing their son to be August.

(Source: Wikipedia)