And I Must Scream: Wormtongue. Eirian has a really vicious streak. Wormtongue is cursed to have a crippling fear of seven particular people and their swords, to have 3 eternal marks on his face so people can instinctively know what he has done and to forever age and suffer wounds without being able to die until he redeems himself.
Audience Surrogate: Harry serves as one in that he makes all the snarky comments that an LOTR fan would make whilst watching the films:
Gimli: Fangorn... what madness drove them there?
Harry: You mean apart from the ferocious battle and certain death behind them?
Badass Family: The House of Eorl, especially since Harry is an honorary little brother.
The Ap Derfel family especially since Merlin is it's patriarch and his wife is Nimue.
Badass Grandpa: Théoden survives duelling the Witch-King and has him on the freaking run until the tables get turned, Saruman anyone who can curbstomp Harry and Gandalf the Grey working together is most definitely this trope, Gandalf and Denethor.
And Galadriel's gifts to Harry: A surcoat in Gryffindor colours and helmet.
Blood Knight: Harry and Sirius. The rest of the cast think they have issues, and since both are probably suffering from PTSD and God knows what else, this isn't surprising.
Brain Bleach: several times, always Played for Laughs, and mostly related to what Harry and Ginny do when they are alone. Points go to Ron (who asks for Firewhiskey) and Boromir (who asks Eru to wipe the images caused from some comments made by Ginny out of his mind).
Bring My Brown Pants: Harry snarks in a moment of dark humour (when keeping the army marching to the Black Gate well hydrated), 'all the better to piss themselves with.'
When Harry discovers that the lords of Gondor are detaining Aragorn so that those that were gravely injured in the battle die, thus leaving him with less support, he goes to the meeting and thunders about their treason. One of the noble lords soils himself.
Buffy Speak: Harry complains about Aragorn being all 'Rangery' and sneaking up on him.
Butt Monkey: Éomer. Starting a prank war with Harry and Sirius was not his best idea.
Call Back: Théodred orders Emrys never to speak of his face plant ever again in chapter 27. Emrys doesn't, and in chapter 2 of the sequel, the Dramatis Personae reveals that he didn't. He wrote it down. In epic verse, otherwise known as the style of poems such as Beowulf. Then Harry read it out at a feast.
In chapter 24 Legolas caustically calls back to the habit of dwarves forgetting the whereabouts of their secret doors.
Chekhov's Gun: The voice that warns Legolas of a threat to Haldir.
Boromir notes, when brushing up Harry's swordsmanship, that Harry's reflexes are faster than any short of an elf, and others note this as well.
One functions as a chain, each leading into the other, as far back as Chapter 7 of The Wizard in the Shadows. Boromir mentions a Noodle Incident in his past, someone he failed to save because he froze in battle, and mentions that he made sure that the man's son was looked after and given a commission in Gondor's army. Later, at the siege of Helm's Deep, this man turns out to be a reincarnation of Godric Gryffindor in muggle form. Finally, in Chapter 3 of From Out of the Shadows, the man's son is revealed to have low level magical abilities and becomes moderately important to the plot.
Harry routinely breaks one of the laws of magic. This is later explained.
Cool VS Awesome: Harry Potter hunting Ringwraiths all over Middle Earth? The Sword of Gryffindor being used as a medium for the spirit of Godric Gryffindor and beat off an army of Dementors? Yes, this trope definitely fits.
Crack Fic: The main story narrowly avoids descending into this at points. Snippets doesn't bother, and Chapter 4 is a cheerful descent into crack fic madness.
Curbstomp Battle: Harry vs Saruman rounds one and one and a half. Round two goes the other way.
Distracted by the Sexy: Pre Pelennor Fields, Harry is angsting over everyone relying on him to save Minas Tirith. He gloomily says that blowing up Weasley Wizard Wheezes couldn't distract him. Ginny takes this as a personal challenge. One dropped Modesty Bedsheet later.
Harry to Orcs, Wargs, Ringwraiths and other dark creatures (along with Dunlending raiders, though a Dunlending Original Character notes that if the Dunlending raiders stuck to stealing and only did so out of necessity, Harry spared and even helps them).
Expy: Intentionally done with the Dunlendings being the Welsh and the Rohirrim taking the role of the Anglo Saxons. Both sides are portrayed fairly. The author puts this down to being half Welsh half English and thus 'a walking paradox'.
Fate Worse than Death: Sirius, who spent seven years being tortured mentally and physically in Saruman's dungeons
Faux Shadowing / Foreshadowing: Hermione notes that 'at least he isn't The Sentry' in reference to Harry. Yet, lo and behold, a young male hero with long blonde hair, clean cut good looks and incredible superpowers appears. In the work of an author whose motto might as well be 'Power has a price'. And is a Sentry fan. Coincidence, or Trolling Creator?
Fridge Horror: Chapter 5 of Snippets reveals that Eirian was a week away from being taken as a breeder, despite Wormtongue claiming her as his personal whore. A week away, as Emrys notes, from carrying an Uruk child.
Furthermore, he adds that if she had given birth to said child, he has no idea what he would have done.
The Glomp: Everyone pulls this on Harry after his return from the dead.
Grey and Black Morality: Chapter 5 of Snippets all but confirms this, with several of the heroes being happy to take newborn orcs away from their parents, as if they are raised away from orcs, they are, in fact, elves. Ginny is the only one who seems worried by it.
Groin Attack: Harry has a tendency towards this when faced with someone who's either physically stronger or has really pissed him off.
Growing the Beard: since this is the fic that the Author has acknowledged as the one he essentially refined his writing on, it steadily gets better, and becomes more and more AU with the introduction of a couple of OC's and more than one character surviving when they would otherwise have died. As this happens, the chapters get longer and longer and there are fewer grammar errors.
Half-Human Hybrid: Emrys and Eirian, being the grandchildren of Merlin, who happens to half Maia
Hand Wave: Harry's personality. While it bears a lot of resemblance to Canon!Harry, it's different because of the years he spent in Middle Earth.
The linguistic thing, wherein the Common Tongue and English line up. Ginny explains this in two words: Merlin. Meddling.
Heroic Lineage: Lampshaded by Gandalf, when he notes the entire Fellowship has famous ancestors of one form or another. Taken to a nigh ridiculous extent with Harry himself, which the author lampshades in 'Snippets'.
Emrys, like many others with a sobriquet such as 'The Valiant', took the traditional Gryffindor approach to distraction. That is to say, crude insults yelled at the top of one's voice. Sun Tzu would have been proud.
The Dramatis Personae in From Out of the Shadows is completely this trope.
Legolas when Sirius accidentally touches a sore spot.
May-December Romance: Eirian and Sirius. Justified in that they spent at least a year in captivity, and bonded. It helps that Sirius only looks about twenty eight years old when he cleans up, and there is implied to be a Time Stop on Saruman's dungeons.
Ron compares Harry to Batman. Sirius disagrees and compares him to Spider-Man, though notes that this depends on his mood, while Hermione is glad that he isn't the Sentry. This may or may not be Foreshadowing.
As Aragorn notes, 'There is nothing mere about that mortal.'
Twist Ending: Sort of. There are several twists near the end, but none spectacularly derails the plot.
Unkempt Beauty: Eirian, who is noted to be still very attractive despite who knows how long in Saruman's dungeons.
Unskilled, but Strong: Harry both averts and plays this trope straight. His magic is a lot more precise than it once was, and he can cast complex shields with relative ease, but as compared to Hermione or Ginny, he is far less skilled.