Salutations!
Alrighty so, I read through your available work so I could offer some feedback as per your request.
Before we get started I just wanted to point out the first thing to catch the readers eye: Prologue. What you have here listed under "Prologue" is actually just the beginning of your story. It doesn't actually feel like a Prologue, so that's just a technicality to be aware of. Here's some information on why often, a prologue can be skipped. Granted, I don't think that yours should be, but it is more just the beginning of your story so you might just categorize it as part of chapter one.
So, to start off with I will say that I like that you keep your initial pool of characters small. This means that each person we meet will have an immediate purpose and be easily identifiable from the outset, it also keeps the narrative from wandering from character to character looking for a voice so, this is good. One of the things I noticed from the off, however, is your paragraph format. Now, this could be a result of if you're using a phone to write your story or another mobile device but, your paragraphs range in sizes from two sentences to five. This is a little jarring as it creates breaks in the action and narrative that make the flow choppy and distracting. This can immediately bring a reader out of your story.
While it might not seem like it, paragraph aesthetics can influence how your audience reads or how seriously they'll take your narrative. If you have consistently sized paragraphs for the most part and the actual page itself looks neat and even, readers are more likely to settle into the pattern. If you have a two sentence paragraph, then a four, then a three, than a five, it gives your readers a feeling of start and stop which can be off putting. So that's just a technical mention. Like I said, when writing on a phone or mobile device paragraph size can be hard to gauge so, I'd recommend fixing that when you go into editing.
Another bit of advice I always dole out: Watch those -ly words. Often, -ly words are unnecessary and the gum up your narrative. If you can read the sentence and it still makes sense without the word, delete it as it's just extra. Also, -ly leads to another problem: Passive Voice. What this does is it makes us feel like we're being told the story rather than shown. This weakens your narrative and makes it hard for your readers to connect to your characters. So, if a word ending in -ly can be lifted from the sentence and the sentence doesn't change, delete it or, replace it with a word ending in -ed if the sentence needs it. (You might have to rework your sentence but -ed words allow the reader to feel like they're in the now with your characters and is the best way to connect with them.)
Another thing I noticed is that you tend to repeat one sentence descriptors a lot. The example that stood out to me was "an (insert descriptive word) -man with wings." You had already described that he had wings, so reiterating it in almost the same manner every time, actually turns me off as a reader. Readers are already trying to latch onto your story, your world, your descriptions, so re-describing the same thing in almost the same way each time actually seems that you as the author, don't believe your audience is hanging onto the details. Now, granted, I don't think that's your intention, but it comes off as "Does the author think I can't grasp what they're saying?" whether or not it's actually meant that way.
This also is compounded by the fact that, when describing your raven character, you refer to him as a "Bird-Man" 44 times within the space of 13 pages. That is a LOT of saying "Bird-Man" as a descriptor and it's off putting because, I as a reader already know what he is, so being told he's a "Bird-Man" 44 times in less than the space of an actual chapter is overkill on your audience. You also seem to use this descriptor in lieu of actual description. While I know he has wings and that he's skinny, pale, and scarred, I can't really imagine the man's face. You don't have to go into such great detail you'd make Paolini blush, but I know the color of his hair and his eyes and I don't really have much of an attachment beyond "Bird-Man" which, isn't a very helpful descriptor if you really want to flesh out a look for this guy.
This is another entry I found that also brought me out of the story:
"A mutation? An angel? A demon? An experiment? A really, really sick dude with an odd angel/demon and crashing houses fetish?"
The reason is something silly that you wouldn't even expect. It's the use of the "/" instead of the "-" between Angel and Demon. You'll want to use a dash here instead of a slash. Slash works fine in conversation or in rundowns like the one's I'm writing because I'm speaking to a specific person, however, in a narrative it looks wrong and distracts a reader. Again, this is just something for when you edit, so when you go back through you know some of the details to look for.
Okay! So those were some of technicals. Now let's get onto the story!
Now, to a lot of people this might be a pet peeve but, it doesn't bother me in this instance: your main character being a prodigy intellect. Now, I am not a person who likes the "prodigy" character who is "pathetic" but so incredibly smart that everyone around him can't believe how amazing he is for being so forced "unassuming" and whatnot. I hate that trope (Hello Charlie Eppes from Numbers). However, the way you present this character is that he is intelligent but he's unmotivated and pissing his time away while simultaneously being down on himself about it, thereby continuing the cycle of being unmotivated.
This is actually realistic of a lot of very intelligent people. They have it, know they can use it, but they're unmotivated or don't know what direction they want in life, so they just don't pick one. This is an interesting character trait and one that I hope you explore in more detail as you go on, as it's pretty realistic. Unfortunately, we went right from this really cool trait, to a word I didn't understand your usage of. That word is "Pervert." The way you used it, and while I don't know if this was your intention, seemed to imply we were supposed to find this funny or cute. As a reader, I associate the word "pervert" with sex offenders. It's one thing to have another person call him that as a rude slight, but it's very different to have the main character calling himself that. Now, granted, we aren't very far in the story, who knows he might actually be a pervert but, if that is the case, perhaps slice-of-life isn't the right genre?
I think I know where this use of the word came from, as in your own story your guy is a self-described 'Otaku' who has latched onto anime. So he could be using the word in the awkward context himself, however, it wasn't a thought that occurred in his head, it was something that was in the narrative description. When anime uses the word "pervert" I find it also to be liberally applied for "a joke" as it were, but I've never even found the anime usage of it to be funny or particularly helpful for a joke. In real world terms, if you ask anyone who they think of as a pervert, you'll get things like stalkers, peeping toms, gropers and so on. So, I'd be mindful of these associations if your character is not actually perverted.
Now, another thing that happened when I was reading is that the character seems to be aware that there is an author. This passage right here gives me that impression:
"Bird-man stayed exactly where he was, keeping his eyes on Marcus like a...hawk.
Bird jokes? Right now?"
It seems like you're telling him a joke and he's hearing you. Now, if this is supposed to be the case I'm not opposed to an author/creation standoff. However, in the earlier parts of the narrative it's written as though he's not supposed to know he's a character so, this broke immersion for me. If you don't want the author and the character interacting, I'd look out for jokes that the character isn't supposed to be aware of, giving him a reaction. Or if that was supposed to be happening in his head, just apply it to his italicized thought paragraphs and it'll make perfect sense.
Moving on, now I'll approach descriptions! So, you do have some good descriptions in here that are quick paced and easy for a reader to get into. However, in your work it also becomes what I like to call "Drive-by descriptions" where you rapid fire a lot of things at once and then move on to the next scene, though the previous hasn't been firmly established. Case in point:
"Nevermind that his home, his personal space, his bachelor pad of all things Marcus, was totally and completely destroyed. Nevermind that his balcony's sliding glass door was sporting a large hole or that there was glass everywhere or that his television was smashed or even that the bird-man's numerous bleeding wounds were staining his beloved couch."
Two things, first: Never mind is two words so when you're editing, just make sure to come back and nab that one (It's really easy to write it that way and then forget about it. Everybody has done it, not just you). Second: While I know that in this instance it's supposed to be a rapid-fire panic, you do this with many of your paragraphs to follow after this point. Example again:
"He just wanted to have an idea as to what he was fucking looking at.
He believed that his somewhat relaxed reaction was mostly shock because he didn't think even he could have been that calm about a situation like that.
He couldn't wait for the meltdown he was going to have when the shock vanished."
This is rapid-fire detail and I can't actually feel anything the character is going through. To illustrate my point I'll rewrite both bits into one:
"Eyes wide and breath caught, he had no idea what Mothman levels of abnormal stared back at him with it's sharp silver gaze. His heart thrummed steady and his detached mind analyzed the damage to his apartment. He inventoried his shattered sliding glass door, trashed television, rent couch, and blood stained well--everything. He brought his hand up to his face and massaged the bridge of his nose as though nursing a headache.
"The government is putting LSD in your chalk, Marcus." he growled between clenched teeth."
Okay this is not a perfect example, (and by no means do you have to use this at all. It is literally just an example) but in a single paragraph I've condensed two, and added descriptors to help put the audience into the story with Marcus. By condensing and using correct word placement, you can tell more story in less words and keep the pace of your novel up while involving your audience in the story. This way you're also treating your audience as though they're along for the ride with you, rather than watching you ride by yourself.
To this end, some things to help you along: There are more senses than just what you're character sees. Birds have a specific kind of smell, as does blood, apartments (depending on the owner) etc. What's the temperature of the room, or is the state of shock making Marcus cold? We're missing out on some of the soft details of the scene that puts the reader in Marcus's apartment with him, such as the literal 'feel' of the room. (Also, you describe your cryptid character as "shivering and sweating" twice almost within a page of each other. Since we already know he's doing that, describing it again doesn't really help the narrative).
To that end: Marcus's mind. While we are following the character, something that is really slowing down your pace, is how many times we stop the action to listen to a joke or long winded thought that Marcus is having. This paragraph in particular is the best example:
"'Why good day fine men of the law enforcement. I would like to report a rather horrifying break-in. Oh yes it is quite terrible indeed, brought me to tears. Do I have a suspect in mind? Do I ever! Why the fellow is still here, old chap. Description? Well he's naked, makes bird noises, covered in scars, probably an abuse victim, oh and another thing, the bloke has wings dear boy/girl. Wings!... Hello?"
If he was making this joke out loud in a conversation it wouldn't be too bad, but for someone who feels his life is in danger or that he could be having a psychotic episode brought on by drugs or some unknown cause, this long illustration of a joke doesn't make sense. Now, often I find that, something will be going on but we're stopping to hear Marcus talk to himself in ways that don't advance the story like the paragraph above (as he never actually calls the police).
Marcus often halts the plot to re-affirm the things we already know by thinking them again, just phrased a different way. For example these two passages:
"There was a man crouched on his couch.
A tall, handsome and naked man.
A tall, handsome and naked man with wings."
-and-
"But it's a fucking naked man with fucking wings.
And he's bleeding to fucking death on my couch.
This is insane. This is fucking insane. And not even in the fun way."
These two passages are from two different places in your novel and they're almost word-for-word the same, only the first happens within the narrative and the second happens again in Marcus's mind. This means that, the already established details, are being embellished again by stopping the story so Marcus can think it. This really slows down the pace of your story, and because it was almost verbatim the same, I had the same trouble with it that I mentioned to you earlier, which is, that you repeat details almost verbatim every few pages despite that we, the readers, already know them. This can really hurt your story and bears consideration upon editing.
My recommendation to catch this problem is to look for other areas where you may have repeated established details and think about whether or not the repetition is needed. To that end, on to my next section!
Troubles I had with the logic:
Hah, okay I have to say it: If your character is an Otaku, why doesn't he think a crazed cosplayer has broken into his house? If somebody who looked to be human with bird accoutrements was sitting on my couch, I'd assume it to be a costume of some kind (and we all know cosplayers can get some really intricate stuff with feathers so, it's not impossible) and for a man who has previously been espoused to have high intellect, this would be the first logical assumption. I think the illusion could be broken when he tries to help the hybrid, and he scratches him. That'd be pretty solid proof that the claws are attached to a hand and not a piece of costume material. It could be a good way to establish just how close Marcus is to anime stuff as well, if he thinks he's got a cosplayer stalker to begin with. If he thinks maybe this one of a kind thing he nabbed at a convention as a prize was so valuable somebody would break into his house for it, that could be a good line to follow (and embody some of the humor that slice-of-life can be known for).
In regards to him not calling the police when he thought he was having an hallucination/intruder: If he thinks he's having a drug related episode or that this could be an hallucination brought on by something in his environment, it doesn't make sense that he doesn't call the police. If you play that angle that he thinks he's hallucinating, having him decide not to call the cops when he may need medical assistance, doesn't make sense (as we the audience know, he's not actually having one, so he's not having a delusional episode that'd confuse him to the point of not being able to call the police).
So, he either needs to decide to call the police (who, if he sounds deranged enough, could take him to the hospital etc. Then when he returns home and finds he's still got a hybrid on his couch, the scene makes more sense. Plus, if he'd just been to the hospital it might be an excuse to give him more supplies, pain killers, etc. Something that could help his new flatmate) or he needs a more solid explanation as to why he doesn't that isn't "they won't believe me". Even if the experience is outlandish, your character just going to sleep really dumped me out of the story. If you leave someone bleeding for hours, chances are they're going to die and I felt like the poor creature would've expired by morning (as the wounds you described were severe and not mere flesh wounds, and particularly severe if the man's lips were turning blue). This breaks my suspension of disbelief and it also establishes that, no matter how injured, nothing truly terrible can happen to your main cast, so I stop feeling any trepidation for them or worry. This then causes a reader to stop empathizing, which can hurt your story as well.
Okay, let's talk about the chalk. Now, some colleges do still use chalk, particularly in the less well funded areas and old community colleges that have operated nearly the same since their inception. Marcus is not established as working in a nowhere college, granted very little is established about his campus at this point. But the chalk could be a great starting point to also drive home, just how off the beaten path this highly intelligent young man who had the future in the palm of his hands at one point, really is. It'd be a great way to establish tone, so you could really make the detail of the chalk work here, just so long as you make use of it when you can. I know it sounds like a small detail but, certain small well placed details can make all the difference and you've got a really good one here.
I also like that there's a history to his downtrodden state, how he was a fallen prodigy who just can't get back up after one slip cost him something important. Again, a very realistic detail that can really work. I've do doubt you'll elaborate on this later so it doesn't all have to happen right this second, but I really like the idea that you have here with him bottoming out in this dreary end of the line kind of situation. It makes his moroseness at being lonely and no longer held up as being special, more intriguing as a character trait.
I will say, Marcus does not strike me as a man in his thirties. His inner dialogue seems more like a man in his late teens early twenties and not a man of experiences (which, you've established he's had many so, I wasn't certain if this was on purpose or not). If he is you've done a good job of characterizing a man who never fully grew up because his young life was inundated with 'grown up' things. It'd be an interesting bit of character growth to see pan out, so you've got some good raw material with this.
The Raven is a mystery at this point so, there's not much to say there in terms of his characterization, just that we're in the early stages so, we'll see how it goes. All in all, despite that yes, there are lots of things that need editing, literally every novel starts out needing a metric ton of it so, you are actually no different in that regard than others just starting to show their pieces for the first time. You've got good elements, a potentially fun story here, and I think you'll do right by it. All you need to do is throw down some edits here and there to smooth out the kinks and I think you can do it. Ah, but where would I be if I couldn't offer something that makes editing less tedious. I give to you: Editminion! This tool helps to identify passive voice, awkward sentences, word usage that might not be conducive and so on. It doesn't fix every last thing, but, it's a great way to edit that makes editing way easier (plus it helps to train you to find some of these things on your own, so you have less to do in the editing department later).
I hope my feedback is helpful. I know that this is a metric ton of feedback so, congratulations if you make it to the end of this thing! I wish you all the best because I think you have the potential of a really fun slice-of-life story here. I wish you all the best with it!