Rather than returning from King's Cross to the final battle with Voldemort, Harry is summoned across the worlds by the Witch-King of Angmar during the fall of Fornost, a little over a thousand years before the War of the Ring. The Witch-King thought he was summoning Morgoth. He is... displeased.
After being freed following the fall of Angmar, Harry travels across Middle-Earth, trying to understand this strange world he's wound up in, adjust to using his magic without a wand, and above all, find somebody who can help him find his way home.
It is in slow progress, with the author indicating that the story will span a thousand years, presumably ending with the War of the Ring.
The Shadow of Angmar contains examples of the following tropes:
- Adaptation Expansion: The story gives the Dwarves and Elves of the East a far greater role, likewise Scatha and the Blue Wizards. Indeed, of the three Istari who traditionally appear, the only one Harry actually meets onscreen is Saruman, with Gandalf mostly being referred to in passing.
- Ambiguously Human: By the middle of the story, it's not entirely clear what Harry is; while he's still described as a Man by Ulmo, he doesn't noticeably age, his endurance is noted early on to be astonishing, and after a couple of decades in Rivendell, he's capable of keeping up with younger elves in practice duels - though he's still slower than they are. As Daewen points out after the 800 year Time Skip, for someone who spends most of his time insisting that he's 'just' a Man, he comes off as something very different. While Harry is reluctant to concede her point, he wonders about it himself.
- Saruman's recognition that he is a Wizard (even if not one of their order), along with hints of a connection to the Valar (he's capable of some very odd things where their influence lingers), suggests that he's become something like one of the Istari - outwardly human, but subtly more in every respect.
- Back from the Dead: Harry, after fighting Durin's Bane, is offered the opportunity by Ulmo (probably, going by the description of his eyes in sea colours, the fact that Harry's in water at the time, and the reference to being in the waters of Middle-Earth), who notes that he is the first man since Beren to receive it.
- Bash Brothers: Harry and Thorir.
- He's also Bash Siblings with Daewen, fighting alongside her against a number of enemies early on, then against Scatha.
- Body Horror: Mentioned early on as most of the results of the Witch-King's tortures. Harry is considered to be a pitiful sight, who everyone believes will die soon - they reckoned without Harry's stubbornness. Even still, Harry refuses to look in mirrors and reflections for a long time, not realising that in time, with use of a home-made potion to restore his teeth, he's more or less healed.
- Cold-Blooded Torture: What the Witch-King and his servants perform on Harry, at first, before making him torture and then execute others, in a brutal attempt at corrupting him - early chapters indicate that they were partly successful, though Harry manages to shake it off.
- Cool Sword: Cool, and faintly ominous, in the case of Anguirel, sister sword of Anglachel, the sword of Turin Turambar, which is found in Scatha's hoard, and which Harry uses to cut off Scatha's head. Harry ultimately decides to claim it on the grounds that in his hands, it won't be misused.
- The Corrupter: The Witch-King sought to be this to Harry (after he got over his initial fury and realised that Harry could potentially be quite useful), and is indicated to have been slowly succeeding. Harry manages to shake it off after he is freed from captivity, but it takes a while.
- Curb-Stomp Cushion: Harry's ill-fated expedition with Thorir, Fror and Floi (nephews of Nain, King of Durin's folk), to find out just what happened to Moria. While he - naturally - loses the fight against Durin's Bane, he holds the line long enough for Fror to escape and warn people of just what Durin's Bane is, and despite dying in the process, manages to escape in such a fashion as to leave the Balrog holding a grudge.
- Chapter 26 repeats this, with Earnur's ill-fated acceptance of single combat with the Witch-King being interrupted by Harry. While Earnur still dies, Harry's intervention allows his men to recover his body, and his duel with the Witch-King ends up temporarily unhousing the latter, actually hurting him for the first time in a while.
- Determinator: To the astonishment of Daewen, the guardswoman of Rivendell who's dispatched to keep an eye on Harry after he's freed from the Witch-King's dungeons, both to make sure that he doesn't seek out the darkness/wasn't corrupted, and to ease his passing should he start dying, he simply refuses to die.
- Did You Just Punch Out Cthulhu?: Harry vs Scatha the Worm. Harry wins.
- Chapter 26 has a reported example, of Harry vs the Witch-King. While it's not an unalloyed victory, Harry actually succeeds in hurting the Witch-King, something few others have achieved.
- The Dreaded: The Witch-King and Durin's Bane, the former of whom Harry is under no illusions that he could defeat (though later on he proves able to equal the Witch-King in a fight and temporarily unhouse him), and the latter of which he escapes largely through a desperate manoeuvre and pure luck, and which he goes to great lengths to avoid wherever possible thereafter.
- Eldritch Abomination: Harry's contact with the will of Durin's Bane leaves him with this view, comparing it to the evil of Voldemort and noting that it's exponentially greater and more terrible - Voldemort, while vile, just wanted to dominate and rule. His evil was comprehensible, human evil. Durin's Bane, on the other hand, despises everything that exists in the light and wants to destroy it.
- Famed in Story: Harry, despite his habit of not telling his own stories and being faintly embarrassed by fame, becomes this, in large part thanks to the poetic/saga singing habits of the proto-Rohirrim. They dub him Eardstapa (the Wanderer), the tale of Fror (who survived the expedition to Moria), and Harry slaying Scatha and going toe to toe with Witch-King in an Offscreen Moment of Awesome. It gets to the point where Eorl the Young, who himself grows up into this, is hearing bedtime stories about his heroic deeds.
- From Nobody to Nightmare: From the perspective of Sauron's forces, Harry goes from unwanted result of a failed ritual/potentially useful pawn and reliant on MacGyvered potions and parlour tricks, to a well-regarded friend of most members of the White Council (particularly Elrond and Saruman) with a standing invitation to join, one of the few to have faced Durin's Bane and lived (as a result, it holds a grudge), then the slayer of Scatha the Worm, wielder of Anguirel and a wand whose core is a heart-string of Scatha's, a deeply respected adviser to the Dwarves and Rohirrim alike, and one of a very few who's capable of matching the Witch-King of Angmar, temporarily unhousing him, and actually hurting him for the first time in who knows how long.
- Good Is Not Nice: Saruman, as this is most of a millennium before he performed a FaceHeel Turn. Though brusque and at times impatient, he serves as a mentor to Harry, teaches him some important lessons, and personally helps craft Harry's metal and stone staff, with Harry being surprised in large part because Saruman doesn't seem the type to get his hands dirty.
- Greater-Scope Villain: Sauron, as per usual, being the Witch-King's master, and mentioned by Scatha as "my Lord's Apprentice", who had told him of Harry's coming, of what Harry was, and "of what he could have been." Worryingly, he seems to have a definite interest in Harry.
- Humble Hero: Harry remains this, with his being reluctant to accept praise, and even more reluctant to accept offerings of allegiance in thanks for what he's done (though in the case of the proto-Rohirrim, he tends to eventually accept for their sake), and it is noted by Leod that he rarely tells stories of his own deeds.
- In chapter 30, he tries to downplay something he'd just done (create a new White Tree with a seed of the original under Gundabad), pointing out to an entranced Daewen that her ancestral memories of the resemblance to Telperion, one of the Two Trees can't be right - for starters, this seed came from the child of the other tree. This self-deprecation, though, is at least partly because he has absolutely no idea how he pulled something that remarkable off, and inwardly speculates that it has something to do with the fact that it's in a cave that's strongly suspected to be where the Fathers of the Dwarves awoke.
- I Have Many Names: Harry acquires a number, to his mild embarrassment, partly due to the number of cultures he runs into, partly due - in one case - to the lampshaded habit of the Quendi (those elves still living around what used to be Cuivenien) to dole out names like they're going out of style. More notable ones are Id-Ubsat (the Healer) by the dwarves of the East, and the more commonly used Eardstapa (the Wanderer) by the proto-Rohirrim.
- Long-Lived: Elves are The Ageless, while those of Numenorean heritage, Dwarves, and Wizards qualify as this. Harry included, apparently, who is an inexplicable anomaly - unlike other Wizards, he's not a Maia spirit in semi-mortal form. However, he ages even more slowly than they do (if at all) and as Daewen points out after the Time Skip, he's capable of far too much for someone who insists that he's 'just' a man.
- Mentor Archetype: Saruman to Harry during his time at Ironhaunt, albeit of the brusque Good Is Not Nice variety.
- Elrond also serves as a kinder one to Harry during his time at Rivendell.
- Motive Decay: Averted, mostly. Harry's primary aim is still to return home to Hogwarts, and his friends, and he worries about how he increasingly has trouble remembering things like the faces of his friends and the sight of the Black Lake under the stars. However, he does become less urgent about it, partly due to the relaxing influence of Rivendell (he spends about 20 years there, and recognising that, plans to avoid spending time there in the future), partly due to having learned the hard way the need for caution. After the Time Skip, which leaps to the point where Harry would be over 800 years old, it's still in the back of his mind. However, he concedes that even if he went back to the exact time and place that he'd been after dying in the Forbidden Forest, he would be almost unrecognisably changed from his time in Middle Earth (for one thing, he hasn't actually spoken English for about 800 years).
- Outside Context Magic: Harry's magic is repeatedly noted to be very, very weird by the standards of Middle-Earth, while Middle-Earth magic is rather strange to him and causes him a great deal of trouble when he has to relearn how to use magic without a wand. However, there is a degree of overlap: his potions can be replicated by the likes of Elrond (but only with great effort), and Harry eventually develops a sense for the inherent magic of Middle-Earth in a way that baffles even elves. Then he gets a new wand.
- Purpose-Driven Immortality: Implied, and hinted to be related to the Valar. For reasons unknown even to him, Harry doesn't really age, when even other Wizards (who are Maia in human form) show at least some weathering over the centuries. Additionally, after he faces Durin's Bane, he's swept away and encounters a vision of Dumbledore because he's dead. It transpires that in fact he's speaking to someone heavily implied to be Ulmo, who offers him the chance to be sent back like Beren, which he accepts. However, this does not explain Harry's drastically lengthened lifespan, far beyond even the original Numenoreans, and after the Time Skip he's shown to be capable of very unusual things where the Valar's influence lingers.
- Time Skip: Intermittently throughout the story - at first, over a matter of months, then a couple of decades, before chapter 26 suddenly jumps forward nearly 800 years to the year 2790 of the Third Age, with a brief excerpt c. 2500 TA.
- Took a Level in Badass: See From Nobody to Nightmare. Harry gets increasingly formidable as time goes by, though it takes a good long while for him to do so. Early on, he's barely able to get the better of one lesser minion of the Witch-King's, a Black Numenorean at most. A couple of decades later, he's slaying Scatha the Worm, and one Offscreen Moment of Awesome has him challenge the Witch-King and not only survive, but actually hurt him. It's also notable that by the time of the war between Goblins and Dwarves, he speaks with the same kind of authority as an adviser in the court of Thrain as Saruman does in the same capacity at Ironhaunt earlier in the story, acting as a counsellor and power-broker between the various factions, being respected and admired by all of them.
- Undying Loyalty: Harry is offered this by a family of proto-Rohirrim after he saves the mother from a poisoned wound following a raid. Since the daughter of that family married Frumgar, and mothered Fram (who in canon slew Scatha), an ancestor of Eorl the Young (first King of Rohan, who appears briefly as a child in chapter 26), this leads to Harry accidentally acquiring this from the entire Eotheod, somewhat to his bemusement. Slaying Scatha only takes it up several notches.
- Wizard Classic: Saruman, Alatar and Pallando, with Gandalf also being mentioned. Harry himself starts to morph into this, albeit a younger looking version, complete with a staff, courtesy of Saruman. When Harry protests, feeling he is unworthy, Saruman simply points out that any man may walk with a staff, but that it takes a Wizard to make it a Wizard's staff. By the end of the Time Skip, now most of a millennium old, Harry has the demeanour though not the appearance.