Hi! I think it's really great being in your mid teens and having such a passion for writing! I like to read a lot so maybe this advice will help you, just my opinion though so don't be discouraged!
1a. Misspelling of work? or is word a brand of shoe? 1b. His blazer is pseudo? Pseudo in what sense? Is it not actually a blazer and something else although pretending to have the appearance of a blazer? Did you mean to convey a 'psuedo intellectual' blazer? 1c. Too many adjectives here I think, and some are contradictory/unclear. The music is ironic AND happy AND ambient AND mocking him? That's pretty intense and I'd like to listen to something like that! I was confused because I couldn't imagine music that could be all of these things at once, if the reader is confused then the writer has not conveyed their idea properly.
2a. Why is Finn staying with Kirsten if she is potentially psychopathic? Is he mentally ill? Does she have a hot body? Any redeeming qualities? 2b. Alliteration isn't working here.
Looking up, he watched the numbers roll up as the elevator rose. Finn brushed a loose lock of his wavy, brown hair out of his face, as he walked into the corridor that housed his apartment.
3. Now; Finn never asked for any of this. From birth, everything had been given to him on a silver spoon (a). His family was loving, functional and wealthy. Mom and dad, marble stairwells, straight A-s through school, humble, generous, and considerate. Nothing Finn did was for Finn. He always worked with others, for others(b).
3a. Nothing is given to anyone on a silver spoon, people may be raised with a silver spoon in their mouth or spoon fed. 3b. Show the reader Finn is selfless. 'Finn was anxious to get home fast. He knew Kristen was waiting for him, memories of smashed glass darted across his mind. He hurried his step, weaving in amongst the other pedestrians'. - he bumps into an old lady and has to help her with her groceries because he is a selfless person ya da ya da.
4a. Watch your tense. Are/were. 4b. Overused the word after. Sentence is overly complex and I'd like to know more about the sabotage...
With his parents dead, he was left with nothing, and the Sinclair’s completely clueless to everything that had happened(a).
5a. What has happened? The sabotage? The reader hasn't been that informed.
So Finn was given their daughter- forced- into taking their daughter. At first, his new life was mediocre at best, living with her. He couldn’t leave her, unstable as she was. So he dropped out of school, and worked an underground job, 70 hours a week, making about 6 dollars an hour.
As things got worse, Finn had to start paying for a plethora of different repairs. It seemed every day he came home, something else was broken, and it always managed to be more expensive than the last thing. Yet, every single day, Finn maintained a positive outlook. He never shouted at Kirsten, never cussed at her, never hit her(a). He, with robotic monotony, woke up at 5Am every morning, got in the shower, dressed as if he was allowed the decency of professionalism, and headed out. He would spend the day with a smile on his face, internally seething with helplessness and animosity(b).
5a. Why would he? Because he is a 'nice' guy? I'm not being shown. Just told. 5b. What 'undergound' job is he working where he must smile constantly dressed in professional attire? A maniacal mobster? The manager or an underground subway station?
Upon arriving at work, he was given a large plastic tote filled with boxes of a specific product(a). He was to load it into his car and stay out for however long was deemed necessary, going door to door, trying to sell that product. At nightfall, he would returned the tote, and went back to his apartment.
6a. 'Specific product' - is this a place holder for the specific product your going to mention later on? Why not just say specific medical instruments or specified transmorfic ghastly remains in an urn for $1?
He reached the 7th door on the left of the hall way. The crumbling rat’s nest he called “home”. That alone was enough to keep Finn optimistic(a). His home was lucky number 7. Number 7 on the left, just as he was left with nothing right(b). He didn’t want to dismiss any silver lining as a mere coincidence. With each day being substantially worse than the last, Finn was grasping at strings(c). Letting out a low sigh of exasperation, he pulled out his keycard, swiped it though the scanner as went inside.
7a. Is this sarcasm? 7b. I like this sentence. 7c. Is Finn a puppetmaster now? Finn is grasping at STRAWS! Possibly trying to find something to dislodge the silver spoon in his MOUTH.
Almost instantly his foot hit a puddle, accompanied by a small sploosh. Across the room, the cabinets under the sink were busted out, and the pipes under the sink were broken, split, softly spilling water onto the floor, flooding the apartment(a).
8a. Kristen is rich? And Finn has been raised with a silver spoon in his mouth yet they are both living in an absolute hovel? No. Those raised wealthy do not live like this, if they did then they would be at more catatonic state than you have described them in.
Before any anger or sadness had set in, Finn was shocked. This was beyond his rationalization. He closed the door behind him, carefully treading forward while ignoring the water coming in at his feet.
“Oh, good, you’re home.” Finn winced upon hearing the bitter piercing voice of his fiancé. “You’ve got a mess to clean up. Or will your sorry ass hire someone to fix it again?” it echoed from the hall way left of the kitchen. “Kirsten, what’s wrong?” he called back “What made you do this? These constant repair charges are starting to p-“ “DO YOU THINK I GIVE A GODDAMN WHAT THER’YE(a) DOING? THAT’S WHY YOU HAVE A JOB, NOT ME!’
9a. Is kristen a pirate or practising ancient norse? If not, then this is a spelling mistake.
Finn turned right back around, slamming the door behind him.
I think you are very creative and a lot of my advice has focused on questions. I think you should show the reader more than describing it to them. I hope you don't think I was too harsh and I tried to be a little humorous! I hope you continue writing and refining your work! I suggest that you read more, and from a variety of different genres and writers!
Hope this has helped a little!