These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Given that it's a hundred and thirty-one years after the events of Halo 3 in-story, and that when we see another of the Chief's Sangheli companions from that time he is quite ancient, and on top of that that N'Tho is quite young, it's possible that this is a descendant, or was named after the original bearer of the N'tho 'Sraom name. Or it could simply be a case of them having the same name, but otherwise having no relation- there are plenty of examples of that sort of thing happening, even on modern-day Earth.
Angst? What Angst?: Though perfectly in-character for him to do so, The Chief, after realizing he's The last Spartan while at Spartan Hill, bounces back pretty quickly, asking Anderson what his next mission will be.
Author's Saving Throw: Quickly and willingly Humanity gave up Artificial Intelligence after the First Contact War. Initially it seemed like a complete cave-in, but a Codex Entry at the end of Chapter 24 paints it as a long-drawn out diplomatic/legal process that climaxed with an incident with a rogue AI infiltrating the Citadel itself.
In addition, it's noted that AIs are still common among humans living outside of Citadel law and influence or working for ONI.
One of the stated goals of humanity and the former covenant races is that if they get a council seat, they're going to bring back Slipspace and AI technology.
On a meta level, the author has noticed that as the fic's popularity rises, he has gotten a wave of new reviews criticizing some of the content of the first chapters and plans to remedy this by removing a few Codex Entries containing already existing saving throws to said chapters to placate new readers long enough to keep them reading.
Crazy Awesome: N'tho 'Sraom, and he'll be happy to remind you of that when he isn't actively proving it, Idiot Hero moments notwithstanding.
Creator's Pet: Miranda was accused of being this after her first appearance, but the author got rid of complaints with a logical (if not also debatable) reason, and noted that he didn't even like Miranda. Incidentally...
Love It or Hate It: Chances are you think The Last Spartan is either A - A refreshingly unique take on the Halo / Mass Effect Crossover that does a good job of merging the two universes as well as giving a good portrayal of the Master Chief, or B - A fanfic with a horrible premise in which Humanity doesn't act in a realistic way and the Master Chief is way too mean and/or angsty.
Take That, Scrappy!: Notably averted with Diana Allers, who the author personally has no strong feelings about one way or the other and thus felt no aversions to including.
They Wasted a Perfectly Good Plot: Some fans quite enjoy the April Fools Day Alternate Universe, especially when they saw the second chapter. Unfortunately, the fact that it's only an April Fools joke means that seeing a fully realized version of it is unlikely.
Though a second, similarly lengthy chapter was posted for that story the following year's April Fool's Day.
What an Idiot: N'tho in again, the Thresher Maw chapter and lampshaded no less.