I vehemently disagree with this theory – there isn’t anything that suggests that the Elements were giving her a taste – actually, an overdose – of her own medicine.
 
@Tyrranux  
sorry, man, but I have to call bullwhacky on that fanon, too – she was crying Tears of Pain, not Tears of Remorse. she didn’t become contrite until she was hit by the Magical Rainbow Lobotomy Laser. in fact, she was happy as fuck when her transformation to Sunset Searing (her demon form) was complete! I am sorry if I am coming off as an asshole, but I am just telling you what happened based on what I saw, not what I thought at the time – no hard feelings.
 
 
@sargesprinkles  
my thoughts exactly.

…well fuck me

Probably magnified it a bit in her own head, methinks.

So what you’re saying is that the Rainbow of Light, in addition to cleansing the dark magic from Sunset Shimmer’s body, also subjected her to something similar to Ghost Rider’s Penance Stare?  
… Neat! Also, kinda horrifying when you really think about the implications of it, but it’s still an interesting and surprisingly logical way of explaining how and why things happened the way they did.
 

@JadedGamer  

 
Thanks!
 
(Woah, 2 years already?!)

Headcanon accepted.

As much as I hate Sunset,this could explain her reformation(ofcourse,I still don’t like her.)

I actually came up with that theory too.

@Aquaz
 
Wow, did you figure it out all by yourself?  
Wow, you’re good!

Where does it offically state that this is what she felt when she was hit by the rainbow? This is more your headcanon than it is facts.

That actually explains a lot. Does that mean that part of the movie was an indirect reference to The Crow?

In the words of Keanu.
 
WOAH!

@SnowPhoenix  
The problem with Sunset, though, is that we’ve got a pretty bad case of “Tell Don’t Show”. I really think it would’ve worked out a lot better if there was a flashback of her time under Celestia and it probably doesn’t have to be that much. Like during that scene where Celestia talks about Sunset, have a flashback of a bright-eyed Sunset being taught by Celestia, but over time, show her getting impatient, bitter, and frustrated eventually leading to her leaving Equestria. And perhaps for added drama, show Sunset and Celestia arguing before she goes through the mirror.

@SnowPhoenix
 
That work too, but only if a person is smart/sane enough to recognise defeat and admit of his/her past mistakes. Some people are so stubborn, even confronted with the truth with rock solid facts, that one will still refute the obvious. The most power that person have, the most powerful that effect become. It’s like they live on another planet or something.  
(See all those politicians that fight tooth and nail in court to defend all those zero tolerance actions that destroyed the life of countless children and teens.) It’s sure that Sunset Shimmers was like that.
 
So, what you said make perfect sense, but only combined with my theory. Because a stubborn asshole who is always right can only see the light if that one can feel the suffering of his/her victims.

@SnowPhoenix  
meh, i think i’d just belt out a frustrated “God damn it” and then run off to commit my next wacky evil scheme

I think the after-effects of Sunset Shimmer’s defeat make sense regardless of what the Element of Magic actually did.
 
It’s made pretty clear that Sunset Shimmer is the type of pony/person who will do whatever it takes to get what she wants, but Celestia’s tale of Sunset Shimmer’s history also makes it clear that she’s very impatient. The cruelty, dishonesty, and aggression wasn’t part of her when she started as Celestia’s student, but instead that behavior was adopted by Sunset Shimmer when things weren’t going as well as she liked as quickly as she wanted them to. Unfortunately as long as this behavior remains effective, it perpetuates, and it was effective for her through her time in Canterlot High. An additional thing to remember is that Sunset Shimmer has made it her life goal to rule Equestria. Her underlying reason for that is unclear. She probably just wants to be the best and admired by everyone, but regardless, the reason for her goal is not important to understanding the emotional impact the defeat had on her. The fact that it was her goal will suffice.
 
Now onto the defeat itself: After years of lusting after it, Sunset Shimmer acquires the crown through her own vicious means, but it rejects her outright, granting its power to Twilight and her friends instead. With Twilight’s words, Sunset Shimmer realizes that all her effort was for naught. Not only have her plans failed in helping her acquire the power she wanted; they’ve actually driven her further from it. This would be very traumatic to anyone who had spent years planning a method of obtaining the crown’s power. How could it not be? The impatient-by-nature pony has wasted at least 30 moons/2.5 years of her life and probably more on a plan that has gotten her absolutely nowhere except even further from her goal. She thought that at the end of the night, she’d have everything, but instead she’s ended up with nothing. She has no friends, her hopes and dreams of claiming the crown’s power as her own and taking over Equestria have been shattered, everyone in the high school except for Snips and Snails stands united against her, and she certainly can’t return to Equestria and face Celestia after the failed attempt to steal the crown’s power.
 
I think that most people in a position like that would cry and beg for forgiveness.

@Psyga315  
i did  
and i’m even madder that you had replaced that memory with “Master of Disguise”

I already headcanon’d it, though it involved the Element of Magic being a self-aware dick who turned Sunset into a demon because he wanted to play “Jackass Genie”.

@sargesprinkles  
Hi there, Batman!
 
I see you recovered your memory of us mindwiping Dr. Light. :P

Headcanon?  
headcanon.

@Background Pony
 
I agree completely. For some reason fandoms just seem to be drawn to behaving that way. When its it as debate its great and fun to watch, but when it turns nasty you can’t help but facepalm at it all.

@Kanrabat  
And that’s what it’s really all about: nothing wrong with making your own theories, but if you take them SO seriously, it’s not going to be a lot of fun if and when they get crushed. Also, many fans (luckily not as many in this fandom as in certain other fandoms), hate on each other over their theories, which is sad and frustrating to see.

@Background Pony
 
I’m sane enough to take my or any headcanons with a grain of salt. Because sooner or later, the real canon will CRUSH the headcanon without mercy. Each times that happen, I’m okay with this, and I frown and tsk at everyone who go apeshit in a shitstorm over that.

@Background Pony  
True, I just feel that, for the sake of fairness, it should be noted fans have been doing this since the show started and taking their own headcanon as the word of faust.

@Bronitarian
 
@Kanrabat  
People are going to over-analyze with everything, that’s to be expected, it just puzzles me that they seem to believe so deeply that this is what the writers Meghan was thinking when she wrote this, which I would bet pretty much anything wasn’t the case. Over-analyzing is fine, but it’s nice when people don’t take their own headcanons SO seriously. Headcanons are just that - headcanons.