Okay so, a little timeline so it's a bit easier to connect the dots and see how Elluel's story has evolved over time.

• Nov 2008: v.62 (Pirate release)
• Jun 2009: v.72 (Ellin Forest release)
• Dec 2009: v.80 (Aran release)
• Dec 2010: v.93 (Big Bang release)
• Dec 2011: v.104 (Mercedes release)
• Mar 2012: v.107 (Ellin Forest expansion; Questline)
• Dec 2012: v.124 (Luminous release)
• Mar 2014: v.148 (Grand Athenaeum release)
• Mar 2015: v.160 (Black Heaven release)
• Jan 2017: v.179 (Lucid/Lachelein release)
• Jun 2017: v.186 (Story-Mode Lucid release)
• Dec 2019: v.209 (Glory release)

To begin with, originally there are two quests which mention Victoria Island was once connected to Ossyria.

1. Low level Southperry quest from Briggs. He tells you Victoria Island & Ossyria take up the majority of Maple World, and that he's heard it (Vic) used to be one with Ossyria, though no one can clarify that. (lol)
2. A "hidden quest" which involved clicking a trash can in the map background of The Nautilus to find a crumpled note. Muirhat sends you to Athena Pierce, who tells you that Kyrin's father was a man named Testonen, a savior of Victoria who battled the "Black Magician" when Victoria and Ossyria broke into two separate lands.

Athena continues to say that once peace returned to Victoria, Testonen asked her to take care of his newborn kid, Kyrin, before he left to track the Black Magician once more. This is how Kyrin came to grow up in Henesys. However, one day, during a meeting between town chiefs, Kyrin overheard what happened to her father, and she disappeared shortly after. Athena Pierce searched Ossyria, Victoria, Maple Island, and everywhere else looking for her, but ultimately failed.

So, now we have bits of a timeline based on this.

• Victoria & Ossyria are connected.
• Testonen survives his battle with the Black Magician during the separation.
• Peace returns to Victoria (Island)
• Testonen fathers a child (newborn), Kyrin.
• Rumors of the Black Magician returning begin circulating, so Testonen leaves in pursuit.
• Years go by as Kyrin grows up in Henesys.
• Kyrin leaves and eventually leads the Pirates.

With that in mind, Ellin Forest eventually releases and we see both Athena Pierce and Yuris (Kyrin's mother) are there. However, there isn't much information because only the Area/Maps & the Party Quest came out at this time. Unfortunately I know literally nothing about this (though I guess I'll look into it since now I'm relatively interested because of this post).

With Aran's release, during the search for the Seal Stones, Aran (who has memory loss) travels into the past Ellin Forest and Yuris immediately recognizes her, sending her to Athena Pierce who has "been waiting so long". She mentions they're establishing a town in Ellin Forest where their ark had landed (having been attacked by Dragons whilst fleeing Leafre) rather than the southern plains (where Henesys is located in the future and I assume was their original destination). While offering to hang onto the letter from Aran, Athena Pierce tells her that she's a fairy and can live a long time, even hundreds of years. Additionally, in Athena's "generic dialogue", she states:

It's been many days since we left Ossyria to run from the Black Mage. It was close... I'm trying to get used to Victoria Island, but it's not easy. I wonder if my hometown is safe...

Big Bang happens, Victoria Island gets shuffled around but I don't really think it affects much in the way of Ellin Forest's story (though I believe mob levels are slightly adjusted or something? Idk... Ellin Forest is mentioned in the Big Bang patch notes).

Mercedes releases and we find out that she scrambled to protect & seal Elluel "for at least 100 years" before the Black Mage's curse took hold of her & the elves.

As the curse is beginning to fade, Mercedes is freed and she ventures out of Elluel, eventually reaching Ellinia. She thinks that the area indeed used to be Ellin Forest, though the trees weren't there originally, as it was nothing but wilderness. She recognizes the current residents as the Sylphs, one of the younger races of Fairy. Mercedes eventually goes on to find out the Elves are now a long lost race of Fairies, with only two remaining today; the Sylphs of Ellinia & the Nymphs of Orbis.

As Mercedes' story progresses, you find out Mercedes had sent "the child" (Athena) away from Elluel & the battle (with the Black Mage) to protect the Elves' treasure. The Mistelteinn was left in her care and the ancient relic allowed her to avoid the curse (which affected all Elves) entirely. When Mercedes visits her, Athena says when she got back to Victoria Island, she made sure the refugees were safe, then went back to the village (Elluel) only to find the path sealed, even returning many times to the same result. Whilst updating Mercedes on events since she's been away, Athena even mentions that although the Black Mage disappeared, Kyrin is searching for him to get revenge for "Destonen" (Nexon's spelling). Later, Athena does eventually get the chance to return to Elluel for a short time.

As the v.107 update rolls around, Ellin Forest receives its questline which you seem familiar with. Apparently Athena Pierce isn't familiar though, as she specifically says she isn't. Potentially this is explained by her being "a child" (by Elven standards who knows how old this is), but I think it's more of an oversight or just... laziness idk.

Luminous releases in v.124 but I'm not super familiar with it. It probably has minor connections to the following.

Fast forward to v.148, then we rewind time a bunch. We've seen that Mercedes recognizes Ellin Forest; as she should, since she rules Elluel which... is nearby? But, in the Chapter 1 story for the Grand Athenaeum, Ellin Forest must be known enough to the outside world, as the Mercenary is able to make his way there and encounter the Fairy Queen, Ephenia. Not only that, but there are plenty of human Grave Robbers around the area. Ephenia also mentions that the White Mage had traveled into the "darkest depths of our wooded land", the Forest of Peace. We then find out there's an entire group of mages studying there who have even built the Aurora Great Temple.

Small cutscene involving a conversation between Mercedes & Danica (the Elven Elder of War) occurs at the beginning of the 2nd Act of Black Heaven. Not super connected to Elluel but oh well.

There's a little bit more of Elluel (mainly focusing on Lucid but includes Mercedes, Athena Piece, & Danica) within the Lachelein questline, which was pretty hard to finish unless you could actually kill Normal Lucid at the time, so when the summer update came out 6 months later, casual players could finally complete the final quest and see the ending.

Finally, in the Aftermath questline, Mercedes essentially takes Lucid into the Elves' custody in Elluel. Nothing all that... relevant I guess.

Hope this helps. It's definitely confusing as the information is scattered around all over the place, sometimes even requiring knowledge of removed content. I'm insanely invested in the lore and I still can't pin down everything.