How did both the Eagle Bearer and their infant sibling survive the drop off the cliff that was supposed to be their doom? A case of Gameplay and Story Integration: The Leap of Faith passive ability, which precludes death from falls, and a latent ability from being Isu descendants.
The nearly identical dialogue for Kassandra and Alexios makes sense when you realize this is an incomplete DNA fragment, so they're cutting a lot of corners as well as filling in the gaps with Herodotus.
There's also the possibility of Schrödinger's Canon being in play - Whichever protagonist you pick determines who played what role in those scenes. (Although canonically, Kassandra is the Misthios and Alexios is Deimos.)
They also have nearly identical lives and home environments despite their different genders.
The Eagle Bearer can get away with practically anything by just remaining hidden, paying the price or by killing the bounty sponsor, and only have a few mercenaries thrown their way instead of being banned from entering cities, attacked on sight etc. People probably assume there's a Man Behind the Man at work and that the Eagle Bearer is simply being paid to commit these crimes, and send mercs to stop him/her while they try to figure out their client's identity.
Nikolaos tells Kassandra to "beware of snakes in the grass." By Assassin's Creed Origins, the Order of the Ancients is collectively personified as "The Snake."
At first, Kassandra being able to take part in the Olympics might seem to be a mistake as the game seems to be glossing over the patriarchal nature of Greek society. Aside from the Herean Games (a women's sporting event that may or may not have been part of the Olympics- historians are undecided)the Olympics were for men only, to the point where it was a criminal offense just for a woman to be in the audience of any Olympic event. However, Kassandra does have the backing of Alkibiades, an extremely powerful and wealthy politican who has a vested interest in seeing her succeed. It probably wouldn't be entirely above him to bribe, seduce, manipulate, or coerce anyone with authority over the Olympics into making an exception.
When Persephone makes a deal with the Misthios to resurrect one of their loved ones in exchange for killing Leonidas in The Fate of Atlantis, Natakas/Neema are mysteriously absent from the choices the player is given. It’s entirely possible that the Misthios never met Darius/Artabanus and his child until some time after The Fate of Atlantis takes place.
Given later reveals in the second chapter, there's a different reason Persephone offers to revive Phoibe or Brasidas - they're both already in the afterlife simulations. Persephone's just dicking with the Eagle Bearer, and never had any intention of honouring her deal.
The Eagle Bearer mentions to Herodotos that the Spear of Leonidas gives them a form of Combat Clairvoyance, allowing them to see an opponent's moves before they happen. In addition to the attack indicators like the flash of a weapon before a strike, this is also a reference to Save Scumming. The player is probably playing through some of the more difficult battles several times, and the Eagle Bearer is benefiting from this: what the player learns through dying repeatedly, the character sees in a flash of insight.
Why does Odyssey have the most 'video gamey' abilities in the series? Even the following game, Valhalla, reins in the flashy moves pretty tightly. The reason is that the Eagle Bearer is the closest person to a pureblood Isu player character to date. Their unnatural abilities are only unnatural from a human perspective, as they're literally a demigod.
Why is Deimos totally unfazed by watching their sibling emerge from the massive self-moving doors of the Great Forge? They've already been in there and fully upgraded their sword, as implied by the pillar inside that matches it.
The "Secret" ending to the Family Arc, where Myrrine will cut ties with the Eagle Bearer, is kind of brilliant in a meta sense. Basically, the way to get it is to promise Myrrine that you would save Deimos, trigger the correct dialogue to do so, but then fight them to the death in the end. Unlike the other bad endings, where Deimos will refuse to back down from a fight and forces the Eagle Bearer's hand, this ending basically requires that you have already done all the work to redeem them... and then chose not to. The Eagle Bearer wasn't unable to save their sibling; they changed their mind about their sibling being worthy of saving, and that is the reason their own mother cuts ties with them.
To those more familiar with Hermes as the messenger of the Gods, his presence in Elysium can seem kind of... random. However, Hermes original role in Greek Mythology was to be an escort of newly departed souls in the afterlife—not dissimilar to Charon. And what is Hermes' most prominent invention in Elysium? His teleporters which are used by the departed souls to get around.
To any player who has played Assassin's Creed Origins, you'll recognize more than a few of the statues dotted around Greece as nearly identical to some of the ones found in the Roman settlements in that game. While there's surely a practical time-and-money-saving reason for this, this is actually true to life. It is well-known that the Romans often recreated Greek statues, and many of the ones which survived to present day are actually Roman copies rather than Greek originals.
The Eagle Bearer has a child with Darius's child in Episode 2 in "Legacy of the First Blade." Considering the ending of the game, the Eagle Bearer will end up outliving their own descendants because of the immortality given to them by the Staff of Eden, as well as not dying until they hand it off to Layla in 2018.
The beginning of Episode 3 pretty much confirms this.
At the beginning of the game, we learn that a mysterious group of rich men have arrived at Kephallonia apparently on a business deal with the Cyclops. When we are finally introduced to Elpenor it starts to become more evident that their main interest is in the Eagle Bearer, but it also appears that they did some measure of business with the Cyclops (presumably that was what he was doing while he was away from the island). It makes you wonder if the Cult of Kosmos was planning to recruit the Cyclops or, at the very least, considering him as a possible ally. By killing the Cyclops at the start of the game, you may have just barely prevented Kephallonia from being overtaken by the Cult without even realizing it.
Alethia mentions she has some other Isu working with her. When Layla and the Eagle Bearer meet her in "The Heir of Memories", she's all alone, and the other Isu go unmentioned. If they died, that'd be one thing, but Alethia has uploaded her mind into the Staff. So did she do the same for her buddies, or didn't she?
The "Fate of Atlantis" DLC adds a new wrinkle of horror to Isu tech. Origins hinted that being geographically near an active Apple could result in a copy of a being's mind getting uploaded to a virtual world (the "afterlives" Bayek explored). But then Episode 1 of "Atlantis" has Leonidas as part of Alethia's first simulation. So either he's a tremendously good recreation of the guy... or it doesn't have to be an Apple, just any Isu artifact. Now think about just how many of those there've been through the centuries...
The various mythological monsters the Eagle Bearer meets are revealed to be an Isu experiment which went wrong (or possibly, far too right). Which might be what the "ghost pharaohs" in Curse of the Pharoahs were as well: An Isu experiment with an Apple left unattended, until someone stumbled on it.
It's more or less outright stated that Chrysis' job was to find orphans to hone into soldiers for the cult—which is how Deimos ends up they way they do. This means that any time you mow down a cult guard, you are potentially killing someone who was just as much a victim of Chrysis' torture and indoctrination as your sibling is. Except, unlike with Deimos, who it is possible to save, you can't do anything for them.
In the Monger's sex dungeon, you can find casts of what appears to be the casts of the faces and breasts of multiple women hanging on the wall. While it's possible this is just erotic art, the Eagle Bearer's perturbed reaction to the casts combined with the fact that they appear to be life-sized and to scale of the average human being suggest something more sinister. Considering the copious amount of blood also found there, it's not out of the question that this "art" is the casts of the Monger's previous sex slaves who have since been disposed of.
Disturbingly, the Mook who finds the Eagle Bearer snooping inside implies that the slaves are just anyone at all who has ever caught the Monger's eye. Imagine the terror of living in Korinth and knowing that you could end up living a Fate Worse than Death just because the local crimelord happened to spot you and liked the way you look.
Even more horrific; a flashback reveals that the Monger had thought Myrrine was pretty. Who knows what he would have done to her if he'd managed to catch her all those years ago?
During the final confrontation at the ending of the Family arc, Deimos recounts a time from their childhood where they watched a friend of theirs get torn to shreds by a mother lion. They don't offer much context for it, but considering what Chrysis said about "giving Deimos pain", it's entirely possible that this encounter was set up deliberately by her as some sort of twisted "lesson". Perhaps even the exact lesson Deimos took from it: even nature protects its young better than their own parents protected them. It's the double whammy of trauma and emotional manipulation that was Chrysis' specialty.
It's not really noted at any point in the game, but historically, Alkibiades was Perikles and Aspasia's adoptive son. So this means the Eagle Bearer and their sibling potentially murdered both of his parents, all the while they knowingly continued a friendly/flirty or even outright sexual relationship with him.
On another historical note, going all the way in facing down the cult is a grand and epic odyssey to undertake, but in terms of historical placement, it's another case of "too little, too late." Even after pulling the Cult out by its roots in its various places, this won't stop the Peloponnesian War from raging for another 20+ years after the Cult pushed Athens and Sparta into this prolonged conflict. And by the end of it all, not only will Athens lose its luster to Sparta, but everyone will be weak enough that another conqueror from the north will sweep in and take it all away.
A whole lot of Adonis' situation becomes very uncomfortable and sad the more you think about it. The game plays somewhat coy about it, but in the original mythology Adonis was taken down to the Underworld by Aphrodite to be raised by Persephone, who "fell in love with him" when he grew up exceedingly handsome—basically, making him subject to Wife Husbandry (or in this case, Husband Husbandry) twice over. Then, Persephone traps him in Elysium against his will. Just when he starts to connect romantically with the Eagle Bearer, his only Love Interest who didn't partake in grooming him, Persephone blinds and disfigures him.
Awakening Atlantis requires all four of the Isu artifacts that spawned mythical Greek monsters like the Gorgon or the Minotaur. However, the Fate of Atlantis DLC shows that these artifacts were the result of Project Olympos, a failed and horribly amoral weapons development project that was the reason why Atlantis sank beneath the ocean in the first place. Why would Olympos' shunned legacy of all things be the key to unlocking that which was destroyed to stop it?note The mundane answer is "because the base game and the DLC were made by different Ubisoft studios that don't talk to each other, and because Ubisoft has long since given up on telling a coherent Assassin's Creed story anyway", but that's nothing the game itself ever tells you, let alone cares to explain.
Perhaps the artifacts already existed for this purpose and were stolen and modified for the Olympos project.
