Since the Isu group the Capitoline Triad was part of appeared to have to been based in and around a large snowy mountain, combined with Isu being much taller than humans on average, it makes sense for Eivor to relate them as Jotnar, or frost giants.
To fit alongside the theme of the cyclical nature of things, of how events repeat themselves over the course of time, the Jorvik assassinations are all reminiscent of assassinations in the first game - the Firebrand is burning the collected knowledge of the city, to the point of burning a priest who questions the act, and having body doubles to make it harder to identify them, much like Jubair, the Needle is a greedy merchant, like Tamir, and the Vault is setting out to poison the nobility of the city, like Abu'l Nuquod.
One also has to wonder how much of the cycle theme is commentary on the series itself.
Considering Eivor seems to run on Achievements in Ignorance, it makes sense that they would view the downfall of the Isu and Odin's efforts to stave off his own death not as what actually happened (an ancient civilization's doom with several members of said civilization finding a way to cheat death), but rather as the story of Odin, the Norse Gods, and Ragnarok.
How does King Burgred have a connection to the Zealots? His wife, Aethelswith, is Aelfred's sister and while probably not an Order member has the sort of connections for Burgred to be able to have them do a hit job against Eivor.
Rowan's advice to Eivor to speak to Synin because "ravens like that" may have a grain of truth to it. Ravens and other members of the corvid family are known for being highly intelligent birds demonstrating things such as knowledge of buoyancy and tool use. Ravens have even been known to mimic human voices better than a parrot can!
Eivor is much more violent to wolves with their kill animations than other enemies; as a child, they were "wolf-kissed" by one while on literal thin-ice, right after their parents were murdered by Kjotve and his clan, and their village was burned to the ground. Getting attacked by a wolf after surviving all that would naturally make Eivor brutalize any wolf that tries to attack them. And that's not even getting into Eivor being a Sage of Odin, who himself had quite a strained relationship with wolves due to that Fenrir business.
Fulke displays a strange fascination with the Isu, to the point of revering them and religiously studying their artifacts. She also goes under the name of "The Instrument." There is another faction called "The Instruments of the First Will" which wants to restore the Isu, which probably originated with her.
It also offers some insight into how the Order of the Ancients became the Templar Order. It's likely that at some point the Order ran into internal conflict due to conflicting interpretations of its ideology (i.e. restoring the Isu vs. taking their place) causing its members to break off into separate factions based on what they believed to be correct.
Basim/Loki assumes Sigurd is Odin's reincarnation, and only realizes it's really Eivor near the end of the story. Since the game all but states that female Eivor is the canon version, it's entirely likely that Eivor was Beneath Suspicion simply because Loki assumed that Odin - who was male - would also be male in his new body.
Also the wolfbite scars Evior has obscured the mark all Isu reincarnations have on their necks.
While not immediately obvious, Aelfred and Fulke couldn't be any more different - Fulke, an Action Girl, is at first played as an ally, but is later revealed to be evil. King Aelfred, a Non-Action Guy, is initially played as an opponent but is eventually revealed to be an ally. While Fulke is devoted to understanding Isu culture, Aelfred is devoted to serving Christ. Fulke works alone while Aelfred is almost always surrounded by guards. She's imprisoned unwillingly, while he exiles himself and starts Walking the Earth. She dies and leaves no legacy, while Aelfred survives, resurfaces, and is still known today.
A clue into figuring out the true nature of the Asgard/Jotenheim visions is actually dropped into the player's lap via the Database. Angrboda's Codex entry states that one of her given nicknames is "the Truth-Giver"; likewise, Aletheia is the personification of the spirit of Truth, hinting that they might actually be one and the same.
Odin trying to persuade Eivor to consign Dag to Helheim after Eivor kills him in an honorable duel is a little jarring, given that Odin is said to welcome any Vikingr that dies honorably and/or in battle. Then again, given that Eivor is a sage of Odin and Odin’s very reincarnation, he may just consider Dag’s challenge not as an act of disrespect and calling out of Eivor, but a direct act of treachery and disobedience against Odin himself.
For that matter, the nature of Dag's betrayal. Is it because he thought that Eivor was a selfish leader who was more about their own glory than saving Sigurd? Or is it because Dag hated the fact that he had to take orders from a woman?
Basim mentions having a son who died years before the game started. While it is unclear whether he's talking about Fenrir or not, assuming he isn't may hint towards what reawakened Loki's personality. Odin and Eivor share their hatred of wolves, Tyr and Sigurd share the trauma of losing an arm, and Loki and Basim may share the trauma of losing a child.
Basim also seems to have mellowed out by the time he returns to the real world. Sure, he's spent about 1150 years in the simulation which is already a lot of time to think about things, but remember that he can actually control what happens in said simulation - it's not that much of a leap to assume he's been venting his rage by creating and then mistreating and/or killing simulations of Odin while he was trapped in the Yggdrasil.
A slightly funny one. There's a flyting challenge in Grantebridgescire where your opponent promises Eivor some cake. Turns out, there was no cake, and Eivor is quite disappointed by the news. So, yes...the cake was a lie.
It's never outright stated, but in the games set in the 18th century, the Assassins are implied to be traditionally allies of the French, (Except in Haiti, for obvious reasons.) while the Templars are likewise traditionally allies of the British - The Assassins align with the French in the Seven Years War and the Templars do the same with the British, the Assassins are involved with the American revolution, which the Templars retaliate against by orchestrating the French revolution, and so on. Assassin's Creed: Unity provides an explanation for why the Assassins have ties to the French - The medieval Templar Order was a mutual enemy of theirs, and they worked together to eliminate its public front - and Valhalla provides an explanation for why the Templars have ties to the British: The Templar Order was born in Britain, founded by the same man who laid the groundwork for the foundation of the Kingdom of England. If Alfred's descendants followed in his footsteps as leaders of the Order, it would only make sense that England, and thus later on Great Britain, would be a reliable ally of the Templars.
The discussion between Eivor and Hytham when Eivor gets the Hidden Blade is an interesting case of Both Sides Have a Point; while Hytham is correct that the sacrifice of a finger has become a symbolic gesture of sacrifice for the Creed, Assassin's Creed Origins revealed that for Bayek, it was indeed a mistake as Eivor noted, doubly so since Assassin's Creed: Odyssey reveals Darius, who invented the Hidden Blade, designed it to be work on the outside of the forearm, not the inside, as Bayek and all Hidden Ones/Assassins do, adding a level of Fridge Funny with the realization that Eivor is technically the only person in about a millennia to wear the blade correctly.
It's noted under Guide Dang It! that the 5 Sigurd strikes have nothing to distinguish them from any other choices in the game, and that it is easy for a blind player to make all the wrong choices, this is entirely the point they are 5 choices that inform Sigurd of Evior's character, and subsequently the player's character through them, these moments, at least in theory (in practice most players will have found an online guide) are the developers pulling a Secret Test of Character on the player.
