The opening song of the TV series "Celebrating the Years" was "Years" sung by Xiao Zhan and Li Guyi. The ending song was "Dream Journey" sung by Xiao Zhan. The interlude included "Life Between Heaven and Earth" sung by Chen Peter,"Years" sung by Xiao Zhan,"Li Jianheng's" Li Ting Yan·Scenery in the Area "sung by Li Jianheng," Unbound "sung by Zhou Shen," Unbound (Chorus Version)"sung by Xiao Zhan and Wang Yibo," Unbound "sung by Lin Hai, Wang Chao and Wang Zitong," Heaven's Will,"Lin Hai, Wang Zitong's "Two Worlds of Beloved Concubine", Mao Buyi's "Relieved", and Zhang Ruoyun's "Drunken Dream".
It's fairly common. Fans often look for more content related to their favorite shows. Since 'Attack on Titan' has a large and passionate fan base, there are a lot of fanfics available. 'Aot' fans might watch (read) these fanfics to explore different scenarios that the official story didn't cover. For example, they might want to see how a certain character would react in a different situation or what would happen if a major plot event had a different outcome.
" A Book of Songs and Songs at the Beginning " was a novel written by the Marquis of Huaiyin, which was about urban fantasy, magical beasts, and wit. The main characters of this novel were Lin Yu, Xiao Luo, Gu Siyuan, Lin Yi, and Wu Guang. The novel had a total of 434 chapters and was completed. It told the story of the protagonist, Lin Yu, who entered a wonderful world with the sacred book of poetry and songs in his hand, which changed his ordinary life. The novel was praised by readers for its novel content, mature writing style, and complete story.
There could be various fanfictions. Maybe some that focus on alternative endings, like ones where certain characters survive who didn't in the original. For example, a fanfiction where Erwin survives and leads the Scouts in a different way.
It could mean that a person who is a fan of 'Attack on Titan' (AOT) is reading or watching fan - created fictional works related to AOT. Maybe they are interested in seeing different interpretations or storylines that fans have come up with.
One way is to check on popular fanfiction websites. Look for ones with high ratings and a lot of reviews. For example, Archive of Our Own (AO3) has a large collection of AOT fanfictions. You can search for the most popular ones there.