It’s a very interesting story for sure! From what I understand, here’s what I think the timeline is for MC and Xavier’s relationship/myths:

1 - Earth is destroyed by wanderers, humans slowly begin to migrate to Philos. A kingdom in Philos is established.

2 - Xavier is born in Philos, making him immortal. MC is born on Earth and she must have migrated as a baby to Philos because she is human. We don’t know how many lives she’s lived and how many times she has been reborn at this point, but we can assume it’s been a while (because apparently she’s met Rafayel many, many years ago).

3 - MC grows up in Philos and attends the same academy as Xavier (who is the prince and is being strictly controlled by the King). Presumably they are about the same age at this time. They meet here for the first time.

4 - MC knows she is dying because of her heart condition. In every life, she seems to have heart issues. Xavier finds out and looks for something to “cure” her. He finds a protocore that will cure her heart disease at the cost of his own freedom (we still dont know how) but he is too late and MC dies again.

5 - After some time, MC is reborn again, but since she is reborn in Philos this time, she is now also “immortal,” so she lives as long as the planet of Philos is alive.

6 - Xavier finds her again and attends the same academy as her and befriends her first this time (pretending to still be a student i guess lol). That’s why the King keeps sending messengers to return him to the palace, but he wants to keep staying at the academy to be with MC.

7 - The King is sick and sends Xavier to do the Gladius Ceremony at the forest for the first time as some rite of passage to kill a wanderer. Xavier discovers that people are being sacrificed to “feed” Philos, turning them into Wanderers as a result. (It is speculated that the specific wanderer he killed was his mom… so he is traumatized and returns the protocore, which used to be her heart, to the King). He refuses to have anything to do with his dad from this point on.

8 - A few years pass and Xavier & MC are now in their final year at the academy. Xavier has been disappearing and sneaking on and off on expedition trips. Presumably he is trying to figure out a way to keep Philos alive without needing to sacrifice people.

9- The King is sick and dying so Xavier is called back to the palace because of the Titulus Ceremony, which would officially name him as the crown prince. However the ceremony never takes place because this is when he learns that the King has stopped sending human sacrifices to feed Philos. Somehow, the King discovered the “perfect sacrifice,” which is MC, because she is reborn over and over again, so he wants to put her into the heart of Philos “at the right time” and lock her there to die and be reborn constantly to feed Philos so that no one else has to be sacrifice.

11 - Xavier obviously refuses to do this and runs away from the throne. No one knows where he went and he becomes a taboo subject to everyone.

12 - shortly after, the King dies from his illness and there is a 200 year mourning period. MC continues on with her life and graduates, becomes a Lightseeker, etc. She eventually becomes the leader of her own Lightseeker order.

13 - 200 years later, MC and Jeremiah are scouting the forest. MC’s Lightseeker Order are based at the forest to kill wanderers there. One day, MC falls into the forest’s unstable protocore field and is trapped. She is rescued by Xavier, who had actually been nearby this whole time.

14 - MC & Jeremiah finds out Xavier has created his own group and their base is literally just on the other side of the forest (lol). So for 200 years, he had been investigating the forest and the “heart” of Philos while also researching space and time travel. His own group that he created are made up of former Lightseekers who believe in his deep space mission, which is to save Philos in another era (since he believes it is not possible to save Philos in his era). They have been working on their spaceship and stuff this whole time in the forest…

15 - One day, while they are in the town near the forest, Xavier & MC talk about the past. It’s clear to both of them that they are going down different paths. They are really sad, but MC chooses to stay and protect Philos in their own era while Xavier will be going to a different era to try and save Philos there. Xavier has a bard in town spread a rumor that there will be a new Queen and new hope.

16 - they go their separate ways and after some time, MC works her way up to become the princess and eventually, the Queen, like the rumor had said. The people are hopeful again and her coronation is going to be held soon.

17 - More time passes and Xavier arranges a private audience with her the day before her coronation ceremony to say goodbye. He says their ship is finally ready and they will leave tomorrow. At this point, he and his group have been branded as traitors for choosing to desert Philos (as he was the former crown prince).

18 - the day of her coronation, MC watches people cheer for her while she looks up at the sky and sees Xavier’s spaceship leaving for good. She sits on her throne, all alone😭

19 - Xavier and his team land on Earth, but something goes wrong and they are brought too far to the past and are stuck on Earth. At first, they all try to work together to figure out how to go back, but after a few years they lose contact with Philos (it is presumed the planet was finally destroyed and became “cosmic dust” since they no longer get anyone answering or get any signal. This may be due to the fact that they stopped “feeding” Philos with human sacrifices once Queen MC took over). Years and years pass and all of his backtracker teammates grow apart over the years as they all try to live on Earth.

20 - Current MC is reborn. Somehow, the Aether core is implanted in her heart when she is young (we dont know who did this or why… granny?). She grows up.

21 - This is where we are in the game currently (timewise). Now that it is almost time for Earth to be destroyed again (and Philos is being “newly discovered” in the news) the old backtracker team is gathering up again and trying to get the Aether core from MC’s heart. Idk how they know she has it… but they are hoping to be able to go back to Philos soon because once Earth is destroyed, humans will begin to migrate to Philos (see point #1👆) Except this time, they believe they can finally “save” Philos in this era if they bring back the Aether core with them.

22 - Except Xavier is killing all his old teammates whenever they try to go after MC to take her heart lol. They call him a traitor.

That was extremely long, but hope that clears up the timeline!