Celestia descended slowly and shakily from her throne, approaching Sunset Shimmer on trembling legs. Sunset looked up into her pale, disbelieving face, fear and uncertainty written across her own.
Celestia lunged forward and swept Sunset up in a great, feathery hug. "Oh, my foolish little pony," she whispered, tears streaming from her eyes. "Can you ever forgive me?"
"F-forgive you?" Sunset said. She swallowed. "Princess Celestia, I—"
Celestia shushed her, spending a long moment simply hugging her. When she finally let go, she took a step back. "Sunset Shimmer...it's true that you disobeyed me, forced your way into a forbidden area of the castle—twice—escaped into another world, and upon your brief return to Equestria, stole a national treasure." She swallowed heavily. "But...I have never been angry with you. Just...just sad. And...and angry at myself." She bowed her head. "I failed you, Sunset Shimmer. I lost my temper with you, when it was clear to me you needed firmer, steadier guidance. Instead of being patient and trying to reach you, I..." She shook her head. "I drove you away. And...and I'm sorry..."
"No," Sunset said. "I...I didn't listen to what you were trying to tell me. I thought...I thought I was better than you, that I deserved things I never really earned." She looked away. "I was a small, petty, jealous foal. I didn't understand..." She burst into tears and flung herself at Celestia. "I'm so sorry!"
Celestia crouched down and nuzzled her. "We've both made foolish mistakes, my little pony," she said. "How about...we start over? Wipe the slate clean?" She smiled. "After all, Twilight Sparkle tells me you have changed...that you finally learned the magic of friendship."
Sunset laughed shakily. "Y-yeah," she said. "I'm...still learning, and I still have a lot to answer for, but...I'm trying."
"That's all any teacher can ask," Celestia said with a bright smile.
"I told you it'd be alright," Twilight said.
Celestia shook herself, remembering the other ponies present. She drew up to her full height, clearing her throat. "Princess Twilight," she said. "And friends. Forgive me, I...I was swept away by the sudden appearance of—"
"We understand," Twilight said. She ruffled her wings. "And if you need time to catch up with Sunset Shimmer in private, we'll understand that too."
Celestia tilted her head. "Perhaps later? If...if you're staying in Canterlot..."
"We'll...probably be here a while, yeah," Sunset said.
Kim stepped forward and bowed as best she could. "Greetings, Your Highness," she said. She glanced back at Ron. "Ron!" she hissed. "Show some respect here!"
"Uhh...I don't know how to kneel or bow in this body, KP," Ron said. "Not and, you know, get back up."
"It's quite alright, I assure you," Celestia said. She glanced at Twilight. "So...who are your new friends, and what brings you here today? Certainly if you simply meant to reunite me with Sunset Shimmer, you would have written first."
"Celestia, these two are humans from a different world than the one Sunset Shimmer lives in now," Twilight said. "One of the Sirens tried to force open the portal to Equestria and accidentally opened a one-way portal to some other world we have no knowledge of. We were hoping to research Starswirl the Bearded's dimensional magic to find some way of locating their home and sending them back."
"I see," Celestia said. She frowned. "The Sirens...they're attempting to invade Equestria?"
"No, not an invasion," Twilight said. She frowned. "The least evil of the Sirens, Sonata Dusk, wanted to come home. Instead of asking Sunset Shimmer for help, she...she tried to open the portal, and it backfired. I've allowed her to return to Equestria temporarily to see if she can really be trusted. She's in Ponyville right now, my friends are keeping an eye on her."
Celestia nodded. "Do you believe she can be trusted?"
"I'm not sure," Twilight said. "I want to think so. From what I've heard, she's been helping these two since their arrival, and is genuinely sorry for what she did to them. She also seems to want to reform, but...there is one problem." She started to pace. "Since she returned to Equestria, her magic has begun to regenerate. I'm not sure what that means, but..."
"I see," Celestia said, nodding thoughtfully. "So it is a matter of whether a creature of dark magic can be reformed. Well...we already know it can be done. Do you believe this Siren can be reformed as Discord was?"
Sunset's eyes widened.
"I think it'll actually be much easier," Twilight said. "Especially since on her own, Sonata's...well..." She shrugged. "Goofy. I mean, she's..." She glanced at Sunset. "Help me out here?"
"She's...a little like Pinkie Pie," Sunset said.
Celestia blinked. Her lip twitched. "Oh my. Well...as to the matter of this Siren, I will defer to your judgment, Princess Twilight. If you believe she can be reformed, and deem it safe for her to remain in Equestria, I see no reason to deny her." She paused. "And the other Sirens?"
"I'd advise against letting them return, Your Highness," Sunset said. "Especially their leader, Adagio Dazzle. If she got her magic back, she'd be a threat to Equestria all over again."
"I agree," Twilight said with a sigh. "It would take a lot to convince me the other Sirens could be reformed." She frowned. "In which case my biggest concern would be whether or not Sonata could accept being separated from her sisters forever."
"I'm pretty sure the Sirens all hate each other," Sunset said.
"Well...the matter of the Sirens, I'll leave to you, Twilight," Celestia said. "In the meantime, the Canterlot Archives and Starswirl's Athenaeum are at your disposal. I assume Sunset Shimmer will be assisting you in your research?"
Sunset smiled. "It's been a long time," she said. "I'm actually looking forward to it."
"But first, I'll see to it that you're all given accomodations here at the castle," Celestia said. She turned to Kim and Ron, frowning. "Oh! I'm sorry, I never got your names. That's terribly rude of me."
"No big!" Kim said. "I'm Kim Possible, and this is Ron Stoppable."
Celestia dipped her head respectfully to each of them in turn. "Well then. The castle is at your disposal," she said. "Sunset Shimmer, I hope once you're settled in, you'll make time to catch up with me."
"Of course," Sunset said.
Celestia nodded to a guard, who stepped forward. "This way," he said.
As the guard led them through the castle halls, Kim mused, "She seems nice."
"Did you see that horn?" Ron asked. "It's like she's got a sword on her forehead!"
Kim rolled her eyes. "I'm pretty sure they don't go around goring each other here." She glanced at Twilight. "Err...do you?"
"Ick. No," Twilight said, making a face.
"Twilight?" Sunset asked. "What was Princess Celestia saying about Discord?"
"Oh, well...that's a long story," Twilight said. "He's...well..."
"He's right behiiiiiiiind yooooooooou," a rich masculine voice crooned. Sunset jumped, spun around...
...and came face-to-face with a draconequus.