It is an alternate version of The Assassination of Twilight Sparkle & Aftermath of a Fallen Star by Rated Ponystar.
The story is the following: One of the conspirators mentions that if Spike was with Twilight when she died, they would have killed him first and made Twilight watch...
...what if they did?
Upon seeing the dragon that she views as son die, Twilight let's loose a magic burst very similar to the one she had as a foal, completely obliterating most of her would-be assassins. She soon becomes obsessed with hunting down ones who conspired to bring about her end, she will have justice for what they did to Spike and no one will stand in her way, not even the elements themselves... or her mentor...
Vengeance of the Star provides examples of:
- Adaptational Villainy: Twilight, as a result of Spike's death.
- Affably Evil: Twilight can still be nice despite her ruthelessness.
- Alternate Continuity: Unlike in the original, Spike dies instead of Twilight.
- Badass Boast: Twilight gives one laced with a death threat after the execution:Twilight: Let this be a lesson to anyone stupid enough to try and assassinate me again. You're welcome to try, but just remember: I won't take your lives, but I'll take everything else.
- Batman Gambit: It's later revealed that Twilight had faked the deaths of the conspirator's families in order to demoralize any future conspirators so that they will think twice about attempting to assassinate her, knowing that that their families will be on the line if they fail.
- Beware the Nice Ones: Twilight, after Spike's death, becomes cold and merciless towards her assassins.
- Bodyguard Betrayal: Five royal guards conspired in the plot to kill Twilight, only to kill Spike first to torture her...which cost them dearly.
- Cruel and Unusual Death: Cosmo the pegasus in chapter four. Flash Sentry and Rainbow Dash beat him severely and then slash his wings to render them useless, followed by Rainbow stabbing him twice with a crystal (first in his torso then in his throat) before throwing him down a deep pit in the caverns beneath Canterlot as he chokes to death on his own blood. Not that he didn't deserve it, mind you.
- Cruel Mercy: The reason Twilight leaves her conspirators alive after executing their families."You three are hereby banished from Equestria, should you ever return, my guards will send you back in worse condition than before." She stated before leaning down and glaring into their eyes. "Now you will know the pain I will have to suffer for the rest of my life, the pain of knowing that your actions have cost you your family, the pain of knowing that you will die alone, with your entire bloodline hated by all of Equestria. The pain of knowing that your entire legacy is now tainted. All. Because. Of. You."
- Dark Is Not Evil: Twilight can still be genuinely nice, even in her dark form.
- Dark Magical Girl: What she becomes when she takes to her Midnight form, both in looks and transformation. However she's an interesting subversion as not exactly evil.
- Dead Guy on Display: Spike is preserved in a coffin encased in several multicolored crystals and given a crypt in the Crystal Empire to honor his heroic actions.
- Despair Event Horizon: Being forced to watch her own son get murdered right in front of her pushes Twilight over the edge and sparks her transformation into a more cold, cruel and merciless pony.
- Exact Words: Twilight said she had no intention of killing her conspirators, but she never said anything about their families...
- Fallen Hero: Twilight is starting to become this.
- Fate Worse than Death: Twilight deals this punishment to her conspirators, stripping them of their magic and banishing them from Equestria with the knowledge that their actions caused the deaths of their families.
- From Nobody to Nightmare: More like from "meek Princess" to "merciless Princess who will kill your entire family and make you watch if you cross her."
- Happily Adopted: One of Twilight's first actions as Princess was to officially adopt Spike, which made his death even more saddening.
- Killed Off for Real: Spike instead of Twilight.
- Kill It with Fire: Twilight orders the families of the conspirators to be burned at the stake, even the foals.
- Mama Bear: After watching Spike die, Twilight unleashes a magic burst strong enough to obliterate her room entirely and kill two of her assassins. The blast was so strong that Rainbow Dash could see it from Ponyville.
- One-Winged Angel: Twilight's rage and anger at Spike's killers leads to her transforming into Midnight Sparkle.
- Please Don't Leave Me: Twilight says this while cradling Spike's dead body.Twilight: Please Spike, please come back... please my son, please don't leave me...
- Recursive Fanfiction: The events of this story are an alternate version of The Assassination of Twilight Sparkle and Aftermath of a Fallen Star.
- Shout-Out: A few are made to the events of original story, indicating that some took place but under different circumstances, for example:
- When Twilight reveals that she simply faked the deaths of the conspirator's families during the execution, she brings up the fact that if she'd left them alone the public would constantly harass and persecute them just for being related to the criminals. In the original story this actually happens to Gladius Stride and Regal, who were the brother and nephew of two of the conspirators respectively, but while Gladius eventually gets better treatment from Celestia, Regal is constantly harassed and bullied to the point where he commits suicide.
- Twilight reveals to Luna that she had a spy listening in on Shining Armor's conversation with Gallant Heart where he reveals that was trying to stop the assassination, only to be forced to choose between his little brother or Twilight when Amadeus found out he was a mole.
- Sins of Our Fathers: Twilight punishes her conspirators by executing their families instead of them and forcing them to watch.
- Twilight indicates that this would've happened to the conspirator's families had she not faked their deaths.
- Tailor-Made Prison: Chapter 8 reveals that Twilight herself set one up in the abandoned Diamond Dog mines, run by Starlight Glimmer. Said prison has various collars for certain criminals, as well as five separate levels for them depending on their crimes. Not only are the prisoners stripped of their Cuties Marks, but hey are also shackled with limiter collars (which keeps non-pony criminals in line as well). The prison itself is also practically inescapable, and trying to flee is a death sentence for Black Collars (who are on the death penalty anyway), as the Dazzlings who patrol the moat are allowed to eat the black collars if they ever try to. Any other color prisoners are immediately hypnotized by their songs and sent back to the prison. Past the moat is an entire forest full of plunder vines that will capture and ensnare prisoners (or rather anyone not wearing Royal Guard Armor) the moment they get too close, draining their magic and leaving them easy to capture when the guards make their rounds. Being a pegasus (or any flying creature) makes no difference since there are spiked clouds in the the prison's airspace that are enchanted to gravitate towards prisoners, ensnaring them before shocking them into unconsciousness."It was like someone took everything that was lethal and menacing about Everfree and dropped it all into this one area."
- Tragic Villain: Twilight, having to watch her son die has turned her into a tyrant.
- Too Dumb to Live: The conspirators, specifically Valiant Wind, who decided to kill Spike just to spite Twilight before killing her, which in turn lead to her undergoing a powerful magic burst that killed two of the assassins and then undergoing a transformation into a more cruel and powerful form. Then he has the nerve to laugh in her face while she has him at her mercy while insulting her and her son, resulting in her ripping off his wings.
- Cosmo as well, for trusting a complete stranger (Rainbow Dash in disguise) with the secret that Amadeus was the true mastermind behind Twilight's assassination attempt and then revealing crucial information about the conspiracy right to her face in his arrogance.
- What the Hell, Hero?: Celestia calls out Twilight when she's about to execute the conspirator's families, only for Twilight to talk her down. Her friends later do the same, but are somewhat pacified when Twilight reveals that she simply faked their deaths.
- Luna later lays into Twilight for executing the conspirator's families. Although not so much her "killing them" as it is her making such a spectacle of it and making her and Celestia seem like her "enablers".
- Twilight then turns it around and calls her out for not warning her about the assassination attempt which lead to Spike getting killed in the first place.
- Would Hurt a Child: The conspirators, specifically Valiant Wind who decided to kill Spike just to spite Twilight before killing her, kicking off the events of the story.
- Written by the Winners: After a previous war with the Griffins, Equestrian historians altered the records to omit ponykind's more darker deeds during the conflict while fabricating others to paint their already defeated enemy in a more negative light. Twilight is currently in the process of rectifying this with her reforms.