At Twilight's castle inside one of the rooms, the boys were practicing some new dance moves to use in their next act. They moved in perfect sync, and were ready for their big finale, until Twilight burst into the room carrying Spike, "Guys!" the boys were startled by Twilight's barging, and ended up falling over and onto each other.
"Ooh." Spike cringed.
Zeck groaned as he looked over at Twilight with irritation, "Twi, you threw off our groove!"
Twilight seeing the mishap she caused smiled sheepishly, "Sorry, Zeck. But there's something you have to listen to."
The band got up, as Josh asked, "What is it?"
Twilight levitated a message up, "I just received this letter from the Princess."
"What's it say?" Tyler inquired.
"She says she's coming by to Ponyville later with somepony who can help us stop the sirens and save Lapis."
"Really?" Damien asked with hope.
"That's what she wrote." Twilight answered.
"Well, that's good news," Derek began, "I mean we've all been stressed out trying to figure out how to rescue her."
"Yeah. Even Damien's been crying in his sleep about it." Tyler motioned to said boy who turned to him with a scowl.
"I did not cry in my sleep."
"Oh, then this isn't you?" Tyler pulled up his phone showing Damien an image of himself in bed looking sad as he slept.
"You took that while I was sleeping?!" Damien snapped.
"It's moments like these you have to capture for prosperity."
"Give me that!" Damien tried to grab Derek's phone, but the comedian of the boys wasn't giving him the chance.
Twilight sighed, "Will you boys get yourselves together for when Princess Celestia arrives?"
"Oh, come on, Twi, this is getting good." Spike replied, as he watched the two boys wrestle for Derek's phone. Twilight scowled at Spike not helping the situation, and used her magic to separate Damien and Derek.
"Twi's right, guys. We need to be ready when Celestia comes, and hope whoever she's bringing can be of some help to us."
"Agreed." Josh nodded.
"Well, Z, you're the boss, man." Derek admitted.
"I'm gonna go get the others, be back soon." Twilight said, as she galloped off. So the boys got themselves cleaned up and awaited for the Princess.
Soon Twilight returned with her friends, "We're here!" Pinkie cheered.
"Sup, guys?" Rainbow asked the boys.
"All good, R.D." Tyler answered.
"Did you see the Princess yet?" Rarity wondered.
"Not yet, Rarity." Josh replied.
"Well, she can't be long now, can she?" Applejack asked.
Suddenly the doors opened to reveal Celestia, "Hello, everypony." she greeted her subjects.
"Princess!" The group greeted, and bowed to her, before rising up.
"It's good to see you all today." Celestia looked over her subjects, before turning to the boys, "And how're your performances going, boys?"
Zeck answered, "All good. Been dosing up on as much positive feedback from our audiences."
"And yet it still doesn't feel enough." Josh admitted with a sigh.
"Well, you'll be happy to know I've found one who can help you with that." the princess smiled.
"Who, Princess?" Fluttershy wondered.
"May I present to all of you, Allegro." floating from behind the Princess was Allegro the siren.
"Greetings, ponies, and Accelerated Dash. I'm joyed to finally meet you." he greeted.
Needless to say the group was in shock at what Allegro was, "A siren!" Pinkie cried, as Rarity shrieked and hid behind Spike.
"Pardon me, Princess," Twilight began sweetly, "But why in the wide-wide world of Equestria WOULD YOU BRING A SIREN TO US?!"
Celestia remained calm upon their reactions, and answered, "I know it seems unorthodox, but Allegro is an allie."
"He is?" Applejack tilted her head.
"How do you figure?" Damien asked, while crossing his arms with skepticism.
"Because those gemstones you wear around your necks are products of my design." Allegro answered.
"Your design?" Josh asked in confusion.
Twilight spoke up, "But I thought Starswirl the Bearded was the one who created them."
"And who do you think helped him create them?" Allegro asked.
"That was you?" Rarity inquired.
"You guessed it."
"So you're a good siren?" Fluttershy hoped.
"I am."
"Well, that's a relief." Pinkie wiped her forehead.
"No kidding," Derek agreed, "Almost had a heart attack." he chuckled.
"Allegro, can you really help us saving my sister from those three sirens?" Damien asked.
"Yes. It isn't right what those three have done to a young girl with so much aspiration."
"You speak like you've met her." Rainbow noted.
"I have."
The group did a double take, as Zeck spoke, "You have?"
"Where?" Damien demanded.
"By a beach close to siren territory. I talked to her about leaving the three because they don't care about helping her. But their hold on her is strong, but it can be broken with the right amount of positivity in one's voice." Allegro answered.
"That's what we've been trying to juice our gems up with but despite all the performances small or big isn't enough." Zeck explained.
"Especially when our opponents have been assimilating energy before we were even born." Tyler added.
"Which is why I am here to help you." Allegro said.
"How can you help them?" Spike wondered.
"Like my fellow sirens, I have also been assimilating energy for a long time, except I have been absorbing positive energy as opposed to negative energy from others. So as you can see I have plenty of reserves which I am willing to share with all of you." he offered.
"Share with us?" Damien asked.
"You mean you can transfer some of the energy from your own gem into ours?" Josh inquired.
"I can. In fact all sirens can, some of us just prefer to hoard all energy to ourselves." Allegro answered.
"And you all say dragons are greedy." Spike told the girls.
Celestia spoke to the band, "Allegro can give each of you enough energy to match the power of the three sirens, giving you a fair fighting chance."
"It'll be the only way to set Lapis free from their control," Allegro assured, "All I ask is that you trust me on this."
"Why do you wanna personally help us though?" Zeck wondered.
"What's in it for you?" Damien asked.
"I can rest peacefully knowing I succeeded in what Starswirl was unable to do."
"Unable to do?" Twilight asked.
"Celestia informed me that you ran into three other sirens before this debacle. Adagio, Aria, and Sonata."
"I have." Twilight confirmed.
"Well, before Starswirl banished them, he himself tried fighting them at their own game by using music, but sadly magic was his true field. So he banished them to the other world in a last ditch effort hoping they would do no harm."
"A lot of good that did." Spike replied in sarcasm.
Allegro continued, "He truly believed that the sirens magic could've been used for good rather than evil, but he lacked the understanding of some kind of magic that you Princess Twilight know of."
"Friendship." Twilight realized.
Allegro nodded, "If he knew the true power of the magic of friendship the Dazzlings could've been changed, but that was his biggest failure. But he swore he would not fail again at trying to help the sirens. When Ballad, Tempo, and Presto emerged some time afterward, Starswirl and I created the gemstones the boys and Lapis wear to be given to other ponies to use to counter the sirens and hopefully show them how better it is to sing to make others happy rather than for selfish glory."
"And you think we can do that?" Josh asked.
"I do with the right help, at least. So please trust me and help me in succeeding where Starswirl could not." he pleaded.
The group thought about it, until Damien spoke up, "I say we do it."
"Damien?" his pals asked.
"If there's any chance of saving Lapis and stopping those three sirens, I'm all for it."
Zeck smiled and answered, "So am I."
"Same here." Josh agreed.
"You know it." Tyler added.
"Accelerated Dash never dashes without the rest." Derek concluded.
"Allegro, we accept your help." Zeck told the siren.
"Thank you. Now Accelerated Dash stand together, as I empower your gems with my own energy, with a little number I've been saving for such an occasion." So the band stood together, as Allegro flew up and began vocalizing to activate his gem which in turn caused the bands gems to glow as well. And then, Allegro began to sing.
As Allegro sang, the girls could feel the passion and sorrow in his voice knowing how guilty he felt being unable to help Starswirl reform his fellow sirens years ago. The boys however started feeling them gems being filled up with energy that was being pooled from Allegro's own gemstone. When the good siren finished the boys looked down at their gemstones that glowed for a bit before dying down.
Allegro floated back to the floor, and spoke, "It is done."
"How do you guys feel?" Applejack asked with concern.
"Felt a little twinge, actually." Tyler admitted.
"I didn't feel anything." Derek answered.
"Did it work?" Damien asked.
"Yes. The transfer was a success." Allegro smiled.
"Awesome!" Zeck cheered, as the boys high fived.
"Those sirens won't stand a chance against us now." Tyler smirked.
"Don't get too cocky, boys." Twilight warned them.
"Twilight is right," Celestia agreed, "Even if your power level has increased to match the sirens, they'll no doubt be prepared for anything, just as you should."
"She's right," Josh nodded, "We'll need all the help we can to get Lapis back."
"Well you can always count on us." Rainbow replied.
"Darn tootin'." Applejack agreed.
"Thanks, girls," Zeck smiled, before turning to Allegro, "What about, Allegro?"
"Me?" he asked.
"You weren't able to help Starswirl against the Dazzlings and only managed to create these gems as a contingency," Josh explained, "How about helping us in the field up close?"
Allegro liking the idea of a chance to make up for what he could not do in the past smiled, and replied, "You can count on me, my friends."
"Perfect," Zeck smirked, "All right, guys. It's safe Lapis or bust."
"Next time they strike, we'll strike harder!" Damien pumped a fist, as the boys got excited.
"We're gonna rock!" Tyler, Josh, and Derek cheered.