After being sick and tired of seeking out for some new friends, reminded to everyone how wrong she really is, and even being left behind in the Human World “good hands” at the end of the first movie, Sunset Shimmer blows up (Not kidding) in a fit of rage after she has another flashback on how she apologize to everyone and regrets all of her actions without even showing and decides to take matters into her own hands instead of being reformed and turning over a new leaf for good, she seeks and gets some pre-villainous advice from Shadow Weaver, and becomes her mentor for the rest of the day.

Here is the prologue:

Sunset Shimmer: Hey, Shadow Weaver. It’s been so long since the last time you died in the finale….
Shadow Weaver: You could spare yourself the trouble if you would.
Sunset Shimmer: Look, we both know very well it was all just in my head. What is it that you want?
Shadow Weaver: To see you. You are the only one I can trust. I’ve missed you, my child.
Sunset Shimmer: I already was Princess Celestia’s student every once in a while. Can we just skip the speech?
Shadow Weaver: Clever. You always were her student. From the moment I laid eyes on you, I know Twilight Sparkle came into the scene after she became princess of the Fall Formal. She was-
Sunset Shimmer: Special? No. What you always told Princess Celestia was that I didn’t matter. I was the ruler of the school only as long until things got thrown into pieces. Why are you here?
Shadow Weaver: Sunset Shimmer, there’s no need for us to be enemies. I can help you get revenge on someone who defeated you, I can offer you a way out.
Sunset Shimmer: [sighs] Then I’ll have to see Twilight Sparkle again. I’m still angry at her for humiliating me right in front of everybody at CHS after she and her friends defeated me in the crater. And what’s worse is that Principal Luna had me fixing up the school after my villainous rampage. [Growls, then gets so angry that her pupils begin to turn red] This.. is… so…. UNFAIR!!!!!!!!! [Sunset’s hair transforms into her enraged form as she gets engulfed into flames, and screams in her fit of jealous rage]
Shadow Weaver: [Amused] Ah…. Look at you. You are like me, and just like me, you’re losing your position with Princess Celestia. I can see that even from your scorn.
Sunset Shimmer: YOU don’t even know what you’re talking about! TWILIGHT SPARKLE GETS EVERYTHING SHE WANTS!!!
Shadow Weaver: Come here.
[Shadow Weaver opens her arms in offering a cool down, looking at her understandingly, Sunset Shimmer glances at her before looking away in contemplation, not wanting to cool down, but she eventually slowly moves closer to her]
Shadow Weaver**: [Gently strokes Sunset’s flames from her hair] She’s earned her trust. How did you let this happen? Don’t you see? You remind me of Catra, you always have. Nothing was ever easy for her either, she wasn’t born to be power-hungry like Adora and the others, she had to earn to be force captain, and fight for it just like Twilight, Princess Celestia wanted her to go further than she did, but you need to be smarter than her, stronger than her.
Sunset Shimmer: Then help me get revenge on her then! She’s the one that put me out on the crater and made the whole student body shun me, which HURTS! Come up with something so you can stay with me…
Shadow Weaver: I will try.
Sunset Shimmer: [Her fiery temper tantrum of righteous rage on her hair wears off and her pupils returns to normal] Are… are you serious? You will do all that for me?
Shadow Weaver: Of course. I will teach you to gain power so you can take revenge, I will be your mentor.
Sunset Shimmer: [Pleasant voice] Really? That would be so nice of you.
Shadow Weaver: Thanks. But, I’m tired now. Come back later, please.
Sunset Shimmer: Okay… [Waves goodbye] Catch you later, Shadow Weaver.
[Sunset Shimmer gets up and opens the door to leave with a slight gentle smile on her face as she exits her way out]

Also, this is another Sunset Shimmer and Shadow Weaver render If you ask me.
To add in insults in injury, most of Sunset Shimmer’s lines were taken from Flame Princess, Adora, and Catra in general.

Sunset Shimmer (My Little Pony: Equestria Girls) belongs to Hasbro and DHX Studios
Shadow Weaver (She-Ra and the Princesses of Power) belongs to DreamWorks Animation Television and ND Stevenson