"If you don't have feelings for him, then why are you getting so defensive? And why are you acting jealous at the idea of him being with me? You wouldn't be doing this if you didn't have feelings for him. Admit it, you like him."
Bilingual Bonus: Brownie says a few sentences and words in Spanish. The most important one is "Arco iris en la oscuridad" (Rainbow in the dark).
Bi the Way: Mecha is revealed to be this after Rainbow Dash wrongfully accuses her of being Brownie's marefriend. Rainbow Dash also briefly says that she tried it at least once.
Bread, Eggs, Breaded Eggs: During chapter four Brownie thinks the only way he won't come in dead last is if "one of the participants was a turtle. Or a snail. Or a creature fusing a turtle and a snail."
Canon Immigrant: Mecha was a character that first starred in another fic by the same author, but she turned into a secondary character because the story was cancelled and he didn't want to waste her character.
Opposites Attract: Brownie and Rainbow Dash could not be much more obviously dissimilar at first glance.
Put on a Bus: This happens to Twilight after becoming a Princess.
The Bus Came Back: But she makes a comeback to help Rainbow Dash and Brownie to solve their problem.
Putting the Band Back Together: Brownie brings back what's left of the Mane Six after Twilight's absence since she became a princess makes them too focused on their work to meet each other, thus damaging their friendship.
Recognition Failure: Played with. The Mane Six are famous all over Equestria, but their real appearances are unknown. Brownie only managed to recognize Rainbow Dash thanks to her Meaningful Name.
Relationship Upgrade: The story starts with Brownie and Rainbow Dash as simple friends, and by the end they finally become a couple.
Sequel Hook: Word of God says at the end of chapter eight that he's planing a sequel. Also on the author's profile page, the story is placed in a section called "Rainbow in the Dark saga" implying there will be at least one sequel.
Slice of Life: The fanfic centers around Brownie's life, starting with his arrival to Ponyville and ending with his first kiss.
Set Right What Once Went Wrong: Brownie tries to fix the mess he caused, but his plan doesn't work. Fortunately, Twilight comes back with a plan that makes Rainbow Dash forgive him.
Stealth Hi/Bye: Done by Pinkie Pie during a few of her encounters with Brownie.
Suspiciously Specific Denial: In chapter five, while taking care of Brownie, Rainbow Dash ask to look in his Portfolio. He says yes, but it's totally not filled with mature stuff. It really isn't. Rainbow even mentions the trope word for word.
Also this little gem from Rainbow Dash:
Iím the only one who can take care of him, like his personal nurseÖ No, take that back, take that back! Iím not a nurse! And that didnít sound totally fantasy-related.
Iím not angry at you because of your asthma. What I really hate is that you lied to me instead of telling me the truth. You could have killed yourself because you were willing to risk your life rather than confessing that you shouldnít go too far. Iíve never lied to you. Why couldnít you do the same for me?
The Reveal: The reason why Brownie was so exhausted as to pass out at the end of the Running of the Leaves and his race against Rainbow Dash is that he suffers from asthma. As he explains, his parents never allowed him to run and play like a normal foal, and this in turn caused him to have low endurance, stamina and speed.
The Tease: Mecha has aspects of this. It's an act, mostly.
The Verse: With the reveal of "The Rainbow in the Dark" saga, it's safe to assume that the author is aiming for this.
Confirmed with Hitmane: Agent 3.14, as it takes place during chapter five. Brownie makes an appearance and Mecha is mentioned once.
Threesome Subtext: Mecha suggests this to Brownie to try and cheer him up. How serious she is is ambiguous.
Throw the Book at Them: Brownie becomes afraid of this idea after Twilight keeps him and Rainbow Dash inside the library so they can finally solve their problems. The book is later changed to a knife when she starts cooking a salad.
What Did I Do Last Night?: Brownie has trouble remembering what happened yesterday after falling ill. He quickly remembers everything as soon as he finds his inhaler lying on his night stand.
What the Hell, Hero?: Rainbow Dash delivers this to Brownie after he reveals that he has asthma and almost died of exhaustion because he kept is as a secret, afraid that she would dump him as a friend given how much she loves to race. Doubles as "The Reason You Suck" Speech.