Ironically, she was the one who led to him getting his cutie mark by saving her from the collapsing book tower…that she made fall over.

Still sad

@LanceOmikron  
I ended up writing a really long examination of Starlight’s eerie origin story, so I’ve posted it on that one Starlight thread.
 
But in summary, Starlight’s own perception of this mundane childhood event must have been far worse than we or Twilight or Spike can fathom.

@hironakamura 
The Joker pulls it off much better, though. Let’s ignore for the moment the fact that Joker has no single, completely correct backstory. The one possible backstory given for him in The Killing Joke explains that he was already having a pretty horrific, life-turned-upside-down-forever day by the time he fell into the acid vat. His skin getting bleached was just the last little bit, the straw that broke the camel’s back, pushing him over the edge into insanity.
 
With Challenge!Lex, it’s not like that at all. By all accounts, his life seemed pretty decent. He lived on a farm and wanted to be a scientist, and Superboy supported that dream after they met. Lex losing his hair was just an accident with no malicious intent behind it (on the contrary, Supes saved his life). Heck, he didn’t even give Supes the chance to make it up to him. So unlike Joker, Lex’s supervillainy in Challenge is entirely based around something that could have been remedied with a bottle of Rogaine.

@LanceOmikron
 
Lol. He turned into a super villain because he lost his hair. What’re you talking about, that’s hilarious. Its like the joker. He fell into a vat of acid, got his skin bleached and decided to be a super villain. Its dumb if its said that way but its funny af.

@hironakamura  
Ah, let me clarify: I have no problem with pettiness in and of itself as a villain/character trait, and I certainly wouldn’t be opposed to seeing that trait explored with her. I just think that her becoming such a monstrously dangerous supervillain due solely to this one particular event in her life is just way too far-fetched to be able to take seriously.
 
It kinda reminds me of Lex Luthor’s backstory from that old Challenge of the Superfriends cartoon. In one episode you find out that a teenage Lex met Superman back when the latter was Superboy, and the two became great friends. Supes built Lex a science lab, and in return Lex later started working on a serum that would remove Supes’ weakness to kryptonite. But one day a chemical fire broke out in the lab as Lex was perfecting the serum, and Lex was trapped inside. Superboy was flying by, saw the smoke, and (admittedly without checking inside) used his superbreath to put out the fire and blow away the fumes. Unfortunately, this accidentally blew the fumes onto Lex and caused his hair to fall out. And because of that, Lex suddenly started hating Superboy and vowed to kill him someday. Because Superboy saved his friend’s life and accidentally made him bald in the process, Lex decided to become a supervillain.
 
In both Starlight’s and Challenge!Lex’s cases, my reaction to their backstory is “…Really? Seriously? What an idiot.”

@LanceOmikron 

 
I don’t think there would be anything wrong if she was exceedingly petty. I think that would be entertaining if an episode revolved around exploring that aspect about Starlight. I want to see her over reacting on really mundane things and have other ponies look at her with cringe and slowly back away.

@Hebbocake  
I wouldn’t quite go that far, but it made her seem exceedingly and uninterestingly petty.
 
Though her stint as a villain was so good (giving us a taste of Sunset’s utterly squandered villain potential) that it convinced me to overlook the weak backstory for the most part.

@LanceOmikron 
Exactly, makes her look like an idiot kid with mental problems instead of a cool villain turned good.

@Hebbocake 
I agree, it’s her biggest flaw. The thing I often say is that her onscreen villainy was excellent, but that her backstory simply wasn’t strong enough to justify the level of villainy she achieved.

@LanceOmikron  
Yeah, it’s like her number one character problem for many people.

@hironakamura 
I am in favor. Strengthening Starlight’s backstory is a must.

I wish the show would have an episode where it focuses on Starlight and Sunburst’s past. Like a flash back when they were kids just to clarify what exactly happened between them. I want to see her bossing him around or putting pig tails on his mane. And then there would be scenes where other colts don’t want to play with Sunburst because they say he has pony cooties. Lol.
 
And then the reason is revealed why he didn’t keep in touch with her was because he couldn’t wait to get away from her. Lol. And then it flash forwards to the present with Starlight angrily chasing Sunburst because she stole cutie marks for the dumbest reasons.

@thps48  
Oh, I am sympathetic with her nowadays.  
It’s just clear she’s got some kind of problem to make this honestly minor event (friend moving away)  
into a traumatizing life-changing situation.
 
Sometimes kids get crazy foolish ideas of how or why things happen (‘cutie marks will take away my friends’).  
and ideally adults will explain or show them why it’s wrong.  
I presume Starlight was too paranoid and/or introverted and/or over-cautious as a kid,  
and never opened up about these fears.

@Hebbocake  
With Asperger’s, I’m sort of more empathetic towards her than other fans are, I’d think. Having identifying personality traits is also a contribution a bit, yeah? <w<

@Amethyst_Crystal  
Yeah.. it’s a given with her character backstory

@hironakamura  

 
I have always assumed this is the case with Starlight Glimmer.

starlight: Im evil because I missed my childhood friend  
vegeta:… and..?  
starlight: that is…  
vegeta: but, that is dumb… but she is so cool… BUT THAT IS SO DUMB!!!

@Princess Trixie vi Equestria  
I read it in Linkara!Superboy Prime’s voice.

Here’s my opinion about this scene.
 
For as long as ponies have been earning Cutie Marks as a right of passage, in all of pony society, how many ponies do you think have had friends who got their CMs before others? Okay, forget the pony thing. Let me rephrase the question. How many of you guys have had friends that moved away? Now how many of you guys turned into super villains?
 
Okay, now I’m not dissing this scene. I think it perfectly makes sense… As long as you think Starlight is really really messed up in the head. She’s obsessing about the event in her life that Sunburst left her… That’s an amazingly hilarious character flaw. Why can’t we have Starlight episodes revolving around her over reacting on the most mundane things and all the other ponies would look at her and slowly cringe away?
 
EDIT: I’m starting to get this head canon that Sunburst may have left her because she had mental problems we don’t know about and he just wanted to get away from her.

When I first watched the season 5 finale,  
this scene and most everything after it was extremely disappointing, to say the least.  
Coming back to it now, this moment is more like an interesting tragic flaw in a character I like.  
If only Starlight had opened up and vented her pain to somepony sooner.
 
@The Toaster Repair Pony  
Yep, she’s definitely completely in the wrong here, and I think she’d agree nowadays.  
@Princess Trixie vi Equestria  
I like making unicorns’/alicorns’ subtitles to match the color of their magic, so maybe that helps?  
I agree with you that issues and problems related to friendship are culturally a bigger deal to Equestrian ponies than (some/most?) human cultures. Comparatively speaking.  
@LanceOmikron  
I think it makes her more realistic in am obnoxious way: getting way too attached to one stupid insecurity or event and making a massive dramatic deal out of it for the rest of their life. Tragic and stupid, but it happens.  
@noobiestbrony  
I knew when I posted this that negative reactions were pretty much guaranteed,  
even from those who otherwise like Starlight as a character.  
But this is a major cornerstone and turning point in who she is in the show, so I wanted to post it still.  
@Josh103  
You could say Starlight had issues with a twisted form of pride.  
@thps48  
I’ve been wondering if maybe Sunburst is actually her stepbrother, and his family took her in. I don’t think there’s anything to disprove that possibility yet.

Man I love angre Starlight. Well, I love any form of Starlight…

@thps48  
I wrote this sentence as it came out in my head.
 
Any resemblance to any known phrase of any series, movie, etc. It’s just coincidence.
 
Also I am not from the United States, I am from Mexico.

@RicardoRenegado  
Your comment’s missing a punchline…

Yes, yes, yes, cutie mark this, cutie mark that.
 
Now you could do us the favor of SHUT UP!!!