Oh Rainbow Dash... It seems these last four seasons haven't exactly been the most flattering for you. The Element of Loyalty is a mixed bag when it comes to actually living up to her title. Over the years, she has received all sorts of unflattering nicknames from the community, many of which we can't even use here with our PGish rating.
This filly isn't all awesome and amazing though. She has a past, and compared to the other ponies we have seen very little of it. From what her trip to Cloudsdale revealed in season one, Dashy has some baggage.
Time to explore her! Time to try to understand what goes on in the mind of Ponyville's #1 narcissistic enigma!
Time to write a giant editorial about a rainbow pegasus below the break.
Lets start at the beginning here, way back with season one and her earliest introduction. Right from the get-go, Dashy was seen as brimming with confidence and not at all afraid to speak her mind. Her very first encounter with Twilight Sparkle involved bragging about her cloud clearing abilities right after covering her in mud and soaking her with a rain cloud. This is just how her character works. Anyone in Ponyville would probably be accustomed to her demolishing their living rooms on a weekly basis while attempting another completely insane stunt right above them. Dash doesn't seem to realize, or care, how much her abilities can actually damage things.
Long neck is long
Her competitiveness is probably one of the biggest factors throughout the episodes that really gets her in trouble. Applejack loves to win, but Dash lets it completely consume her. You know how cats bolt across the room when they see you due to all that pent up energy? That's how I see her. When someone mentions any kind of contest or event, that buildup of adrenaline to prove herself after sleeping in trees for hours at a time suddenly explodes. She will stop at nothing to be victorious, and it always ends badly.
But this leaks over into other aspects of her life. Season two revealed that she doesn't just obsess over winning, she obsesses over everything, and takes it way too far in the process. In Daring Do, she needs to rob the hospital and absolutely cannot let anyone know that she would ever be involved in something so eggheaded as reading. A simple situation quickly explodes due to her needing to keep up this persona she seems to have trapped herself in.
We could call it good at that and start the next section digging into what makes her need to keep up the charade, but lets touch on something that I believe evolved from that aspect of her personality.
Remember that time she almost sold Fluttershy into what is essentially pet training slavery just to get her hands on the first edition of Daring Do? That's some serious obsession right there, and one of the more uncontrollable sides of her personality. In reality, Rainbow Dash would never dump her best flutter buddy like that, but her need to acquire the book temporarily clouded any kind of reasonable judgment. She quickly realized the error of her ways and ended up rescuing Flutterbutt from "many moons of pet training", but the fact that it could reach a point where Fluttershy was ready to be shipped off if the trade council thing didn't convene is scary to say the least. Her competitive nature bleeds over into a need to succeed in all things, taking everything to the extreme.
I could go on and on for pages about all of the douchebaggy things Rainbow Dash has done over the last four seasons, but that's not really the point of this. Lets dig into why she is this way.
Way back in season one, we had the first instance of "Rainbow Dash losing her mind", and it actually revealed a lot about the character that I think many have forgotten over time. Her past hasn't been explored much at all since then, other than brief glimpses of her with her father, or racing the others as a foal.
In Sonic Rainboom, we learn that Rainbow is actually a flight school dropout. While she points out that she wasn't actually expelled, the fact still remains that Ponyville's #1 flyer left what was essentially going to be her future. Even as a grown up mare returning to her home city, she is still tormented by the three above. Ponies may be slightly different than our world in terms of manners and social stigmas, but it still seems a little odd that after all these years the first thing they do is give her crap. Things must have been really bad for her to leave like that, and these three reveal it.
Have you seen her house? That can't be a weather pony budget. I bet her parents are pretty well off to top it off, and well off parents usually means more expectations.
I think it's safe to assume that this may be the period in her life where she moved down to Ponyville (inb4 season 5 has a Dash history episode that completely expels this). An emotionally scarred pegasus pony with massive hopes and dreams joining what is essentially an oldschool earth pony settlement is sort of a testament to how far she had fallen.
Hurricane Fluttershy showed us how uncompetitive the pegasus are in Ponyville. As an elite flyer, Rainbow probably felt pretty awesome being a (partially) trained Cloudsdale superflyer in a sea of casual Ponyvillians. I'm making more assumptions here, but I'm assuming her rise to head weatherpony was a quick one. Those Wonderbolt dreams came back, her awesomeness went to her head, and this is where we are finally introduced to her.
Unlike Cloudsdale, Rainbow Dash worked hard to build her persona. She got a second chance and took full advantage of it when she saw an opening. Unfortunately this lead her down to the path of being... kind of a dick!
With a town sporting it's very own Rainbow Dash fan club, a rekindled desire to join the Wonderbolts, a sudden addition of being one of the chosen Elements of Harmony, and working directly with big names in Canterlot via Twilight Sparkle, Rainbow Dash was both in an excellent position, as well as an incredibly stressful one. She has an entire village looking up to her, and her already competative nature means expecations just keep on rising. Iron pony challenges, impressing Spitfire, Best Young Flyer competitions, and the constant evil bombarding Ponyville only helped to fuel it.
She most likely dreads ever hitting that post-flight school low point again with all of her successes, and this comes out in an aura of douchebaggery. At the end of the day, we have an insecure pony with an incredible amount of talent that probably drives most of her buddies crazy.
That about answers the big question here. Rainbow Dash is both. If she remained in flight school, joined the Wonderbolts, and became the symbol of pegasus flying with no downfall, she'd still probably be a pretty big douchebag. That's just a part of her obsessive personality and need to win, and what makes her a fun character. Add an extra layer of insecurity that compounds it, and you have the Rainbow Dash we have come to know and love throughout the last four seasons, who will be your best and most supportive buddy ever one moment, and sell you to slavery for a book in the next. I feel for Fluttershy sometimes.
She will grow out of it as she matures. The majority of the mane 6 have adult lives but the personalities of Teenagers. I think it was Lauren faust who said she intended this form the beginning. But for the sake of the show, it makes her an interesting character.
This is probably why I just spent a day researching, and 2 hours writing about a cartoon horse. What am I doing with my life.