Why is the protagonist / Sebastian able to shake off a Crucio, when Natsai could not, later on? The spell Crucio hinges on the caster's desire to cause hurt, in Sebastian's words: 'You have to mean it'. In Sebastian/the protagonist's case, it's clear that the moment they cast the spell, they instantly regretted it upon seeing their good friend screaming in agony, making the spell not last as long as it should (though enough to get the door open). On the other hand, Natsai was hit by Crucio by Harlow, who really wanted to hurt the protagonist for killing Rookwood, only for Natsai to take the bullet.
Comparing the two scenes, it's clear that the protagonist was able to take the Crucio a bit better than Sebastian could (the protagonist only fell to their knees while Sebastian writhed on the ground). Seeing as how they were able to coerce Rookwood's Avada Kedavra into a linked duel with Ancient magic, it's possible that same magic is helping them tank the pain a bit better.
Some accurate mannerisms from Ominis as a blind character:
All companions will cast Lumos if the protagonists casts it first, except for Ominis. He doesn't need Lumos to light up his surroundings after all.
If the protagonist casts Imperio on Ominis in one of Sebastian's sidequest, the protagonist will tell him not to move until they are out of sight, but Ominis immediately starts moving. It makes sense because he can't see. Poor choice of words on the protagonist's part.
when you are speaking with he faces you with his ear instead of his face so he can hear you better.
Imperio is an Unforgivable Curse that temporarily turns enemies to your side to fight, but it will only last a while. Why not longer or multiple targets? Because Imperio's strength is based on the user's magical power and the victim's willpower. Despite the list of achievements and their raw power, the protagonist is still a budding witch/wizard whose still on their first year of casting magic and dealing with enemies much older and experienced than them. If their Dark Arts Talent tree is any indication however, it seems as though they will only get more proficient with the spell as time goes on.
When other characters cast Bombarda they take the form of an orange fiery explosion, however, the protagonist's Bombarda is a blue explosion for some reason. It could be a visual change to differentiate the spell from Confringo, but Ancient Magic is always exclusively shown as blue (except for the corrupted variant which is red). As the protagonist has shown the ability to manipulate their spells, they could very well be casting an Ancient Magic variant of the spell, hence the blue color.
The spell Accio can't technically be used on humans, but you can pull in enemies with the charm. As Ominis says in Charms class, you're actually summoning their clothes. It also makes sense why some human enemies are resistant to the Summoning Charm, they're too strong to be pulled by their clothes.
Somewhat turns into Fridge Logic when you consider if this is the case, then how does the protagonist pull living creatures like spiders, dark mongrels and whatnot to them if there's no clothes to pull?
Clothes are made of cotton, which is made of fur.
The fact that Garreth Weasley is the one who tells you about the One-Eyed Witch Passage to get to Honeydukes. After all it was Fred and George Weasley who told Harry Potter about it and had even used it themselves. Seems to be a bit of a family secret that has been passed down.
In the final fight against Ranrok, it's clear that normal spells don't actually do that much damage to him. But what does? Ancient Magic finishers. Seeing as Ancient Magic is used to contain the corrupted magic, it only makes sense that it damages it more too.
The protagonist does a 'sidestroke' while swimming (without going any faster). It's a survival swim technique that is taught to help you keep your stamina during long swims, which makes perfect sense for the protagonist to use while swimming across large bodies of water like the Black Lake or ocean.
All of the main companions share the same trait the protagonist has of being unfetteredDeterminators, standing up and pushing themselves against all odds to accomplish their goals. Despite being a student, Natsai absolves to take down an entire poaching ring by taking down Harlow (Rookwood's trusted number two), Poppy will do anything to help the beasts even if it means murder, and Sebastian does whatever it takes to find a cure for his sister, even it means dabbling in the Dark Arts. Similarly, the protagonist is doing all they can to find a way to stop Ranrok at any means necessary, engaging in all sorts of rule breaking, curses, and killing if necessary. It seems when it comes to friend choices, they have a type.
Ammit being the outlier who only goes on one mission with you makes sense considering his Cowardly Lion status, but also that he apparently doesn't have a Dark and Troubled Past like the others. Really, he's almost vanilla in comparison, but that's because without any real conflict in his life he's never had to develop a determined attitude in the first place.
It might be strange that your character wasn't admitted until fifteen, but if you find the secret key in the Headmaster's office and use Revelio on the Book and Quill of Acceptance, you learn that most likely your character didn't display strong enough magical aptitude until they turned 15 (and the same goes for Percival Rackham and Isidora Morganach). Neville Longbottom even comments his family thought he "might not be magical enough to come" back in the very first Harry Potter book.
During some points of exploring, you can find small piles of pebbles next to bodies of water, such as lakes, and are given the option to interact with them, which will cause the protagonist to levitate and magically throw a pebble to skim it across the water, except you can do this just after your first visit to Hogsmeade, which is long before you learn spells such as Wingardium Leviosa or Depulso. However, it is also just after you unlock your ability to use Ancient Magic, including the Ancient Magic Throw; therefore, it is more than likely the protagonist is using their Ancient Magic Throw to skim some pebbles for fun.
Given Sebastian's desire to cure Anne of her curse, one has to wonder why he learned the Unforgivable Curses. They seemingly have nothing to do with his quest for a cure. But if one takes his character into account and how he's studying Dark Magic, it makes more sense as to why he knows how to cast them. In the order of the spells he can teach us...
Crucio, aka the Cruciatus Curse, is focused on torturing the target subjected by it with the pain and torment increasing with the caster's intent. Given Anne's curse causes her to feel frequent bouts of pain if she strains herself and Sebastian noting in his quest in Feldcroft that he wants to analyze what exact kind of magic it was that affected her, be it Goblin or Wizard magic, it makes sense that Crucio would be the first thing he'd study since he may consider her curse being akin to or a subspell variant of Crucio.
Imperio, aka the Imperius Curse, is focused on controlling other people to the caster's will and getting them to do anything in your name. As said above, Sebastian doesn't know what kind of magic harmed Anne save that it had to be caused by a wizard or goblin. Assuming he found the perpetrator and they were unwilling to undo the spell, he could use Imperio to force them to do so anyways. It would also be good to make potential targets fess up information that he may need.
Avada Kedavra, aka the Killing Curse, is as it's name says focused on killing targets in one hit of it. Considering all the current events around Hogwarts including Ashwinders, Goblins, Poachers and various other dangerous beings, and not to mention Feldcroft is being surrounded by Goblins to the point of fear from the residents of which Anne is one of them, it would make sense that in the face of such dangers, in case his fifth year spellcraft and dueling capabilities aren't enough to save him, having knowledge of how to cast the Killing Curse would ironically be a lifesaver for him and/or Anne if he ever had to use it.
Fridge Horror
It's really not nice to think about how Ominis' aunt actually died in Slytherin's Scriptorium trials. There was no possible way for her to escape or call for help, she had to slowly die from hunger and/or thirst, feeling as though she had doomed her brother, who she had sent an invitation to join her. Not really the way you wanna go out.
No matter what ending you end up picking, the result is the same: there's an unchecked fifteen year old with insanely powerful untapped potential in charge of an equally powerful vault of 'evil pain magic' underneath the school only they have access to (as they are the only one able to use the Keeper's Wand). Not only that, their only adult supervision and advisor (Professor Fig) dies no matter what. Forget Tom Riddle, this fifteen year old is the most dangerous Hogwarts student to have ever exist.
This danger factor gets doubled in the 'Harness' ending, where the protagonist decides to absorb some of this magic to grow even more powerful. Seeing how they were able to have an easier time containing the magic after inhaling it, there's no telling how powerful they're going to become. And this time, there's no team of wizened Professors who understand the extent of this power to stop them. We are lucky that this kid isn't actively trying to take over the world (probably, as Wizardkind is still thriving in the present day).
Even in the Secret-Keeper ending, keeping this unknown power a secret isn't really a good idea either - we're just asking for another Ranrok or Isidora situation to happen, and there is only one defender and keeper of this knowledge, one who's still very much a student. Sure, this teenager can take on thirty Dark Wizard/Witches at once, but they're still just one person. What happens when the protagonist ages out before another Keeper can be appointed? There's still too much that can go wrong.
Presumably the portraits of the other keepers would help the protagonist to rebuild, or replace the scavenger hunt for another keeper at some point in the future, to ensure that the repository is protected. In addition, while Professor Fig is gone, but the Protagonist does have others who they trust, who may be able to help, particularly if they take Fog's comments on how he should have trusted the other teachers (save Black), to aid them, and explain the situation to them as well.
Pretty much the entirety of the cast shrugs off the protagonist casting Avada Kedavra, and it never nets them the same consequences virtually any other character in the franchise would deserve. Gameplay and Story Segregation aside, it almost reeks of abnormal favoritism, as even the professors all but say to never use the spell around them again. In any other instance, it should land you a firm expulsion, but either Hogwarts has gotten insanely lax, or they figure the character can do no wrong. And then no one or nothing stops you from promptly using it to illegally murder any threats in your path outside of Hogwarts. And that's the worst of it; no one really raises a brow about this mere teenage student running around murdering criminals, poachers and goblins all over the place by the dozens even with more standard spells, not even a psychiatric or morality check.
Perhaps part of the reason that teachers are willing to look the other way for the protagonist is because they do have an idea of what they're dealing with. Considering most of the questlines put you in harms way with Poachers, Dark Wizards, Goblins and the various vicious beasts like spiders and trolls, all threats who do not have your best intentions in mind at best and are trying to hunt you down and kill you at worst, utilizing a spell made specifically to kill people in one shot has it's understandable applications. The fact you and Professor Fig were attacked by Goblins and a Dragon is also a well known story in the school, Hecat denotes she knows what goes on in the school and Sharp is an ex-Auror who highly impresses on the students about the dangers outside the school, hence why they all may have more forgivable attitudes on knowing the Unforgivable Curses.
Some of the scars that you can put on your character during Character Customization at the beginning of the game are absolutely horrific. From looking like they got mauled by some sort of wild animal to a magical burn scar that takes up half their face and the fact that your character can have these scars even before the story even starts (before all the dangerous stuff even happens), it's morbid to think about how they actually got them by age fifteen.
Ominis being born blind makes even more sense when you consider the history of the Gaunt Family. In the books they are described as being physically deformed and violently unstable as a result of generations of close inbreeding to keep the bloodline of Salazar Slytherin "pure". Other known effects from inbreeding is blindness, so it is likely the reason behind Ominis' condition too.
Which leads to further Fridge Horror as Ominis is the White Sheep of the Gaunts, a sane and unprejudiced Nice Guy despite his family's influence of both upbringing and genetics, in other words, as tragic as his blindness is Ominis was lucky that he didn't end up an insane inbred maniac like we see Voldemort's relations were later in the timeline.
If one considers the events of the Chamber of Secrets and the events of the Slytherin's Scriptorium quest revealing details on Ominis Gaunt and his family, then one must consider the entire school lucky because Ominis would've been the perfect Heir of Slytherin if he didn't have a hatred for the Dark Arts and Slytherin's anti-Muggleborn legacy. To wit, he and his family basically are the only known qualifiers to have the blood of Slytherin required to control the Basilisk in the Chamber, his blindness renders him completely immune to the Basilisk's Deadly Gaze, and he naturally knows Parseltongue from his time with his family. Had he shared the same sentiments of his family during the Scriptorium quest, he would've had the exact materials to see Slytherin's wishes through and to much worse effect than Tom Riddle would've ever had!
The Defence Against the Dark Arts position might not be cursed yet, but apparently some horrible luck still surrounds it. Isidora Morganach was killed in Hogwarts, and professor Hecat is sickened by some kind of time magic that may or may not still affect her.
Fridge Sadness
The Sadistic Choice of who to cast Crucio on in Sebastian's sidequest gets a lot worse when you take into consideration Ominis' trauma of using/experiencing the spell. Ominis understandably refuses to even consider casting the spell (nor does Sebastian or the Protagonist even willing to consider doing it on him). Instead, no matter what decision was made, he hunkers on the other side of the room, being forced to listen to either the protagonist's or Sebastian's screams of agony. That's going to reawaken some sort of trauma for him.
Any Hufflepuff having to play through the Prisoners of Love Sidequest gets a firsthand look on how horrible Azkaban really is. The inmates are all suffering and have their soul sucked out by the dementors. Now, think about the choice you have to make later on, deciding on whether or not to turn Sebastian in. He would face trial by the Ministry and get sent to Azkaban. And then, he'll likely end up like Anne Thisbe, rotting away in a cell, having gone insane from the dementors. If Ominis' dialogue postgame is any indication, life is only going to get worse for him down that route.
Regarding Anne Thisbe's story, it gets worse when you realize she's muggle-born and that she was just a student as well when she was sentenced to Azkaban. Her muggle parents probably had no idea why their daughter never came home or even that she's been sent to the worst prison imaginable. The worst part is that Anne didn't kill Jackdaw, she just suffered all this for no reason. No wonder she's resentful.
If you are not Hufflepuff, Jackdaw won't ever find out what happened to Anne Thisbe and without his testimony, she will continue to suffer at Azkaban for the rest of her life.
The variant of the Secret-Keeper ending where the protagonist decides to keep the repository as a secret forever as it's sole Keeper, taking on the burden of it all on their own, which also dooms them to a life of isolation and secrecy. Professor Fig had offers his support, but he dies shortly after, succumbing to his wounds. All the previous Keepers from the portraits seemed to have vanished, having 'died' after serving their purpose. Now the protagonist really is alone and the last of their kind. The path they lead as the only Keeper sounds like an incredibly lonely future.
The implication in the 'bad' ending that the reason why Professor Fig was not present for the ending is that he was so shocked by the protagonist's decision to open the repository (either to follow Isidora's footsteps or for their own power), that he was unable to power through his wounds. His last moments is knowing that he may failed the protagonist and Wizardkind.
It's implied that the protagonist was born into the Wizarding World, as they seem quite knowledgeable about the world, culture, and magic. Near the beginning of the year, the protagonist even remarks that they've been waiting to attend Hogwarts for a long time. Since their magical ability didn't manifest until fifteen, this meant that the protagonist was likely perceived as a "squib" (a person born from a magical family who isn't magical) until that magic manifested. Knowing how difficult squibs have it in life and the discrimination they face, it's certainly possible that the protagonist probably didn't have a very fun childhood.
This gets doubled if you decide to canon your character as a Pureblood, especially if they're a Slytherin. Knowing how some Wizarding Families are obsessed with purity, having a possible squib in your midst would not be per their status quo.
Poppy's backstory. As noted elsewhere, when she ran away from her family, she was no older than 10, while she ended up happier with her gran and witnessed a dance of mooncalfs, she was likely terrified.
