A few minutes earlier…
Ace walked along the path along Sweet Apple Acres from Ghastly Gorge and the race, kicking along a small pebble as he did so. He was looking down steadily, sniffing sadly as he kicked the rock. "I can't believe I have to go back…" He said aloud and he kicked the rock again. He walked forward and stopped in front of the rock, "Back to Earth…"
Ace suddenly roared in frustration and kicked the rock harder than he had before, sending it spiraling through the air. Panting heavily with anger and frustration, Ace watched the rock as it flew before it finally disappeared into the apple orchard.
Ace stood there for a moment, still panting heavily with his eyes narrowed, his eyes fixed on the horizon. "Not only is it not fair to me…" He said aloud. "It's not fair to any pony who has known me either. For me to just disappear like this is just-"
Before Ace could finish his statement, an ear-shattering boom sounded in the sky above the orchard.
"Rainbow Dash?" Ace looked up, confused.
To his utter surprise, instead of a Rainbow shockwave blanketing the sky, he saw a blue and grey shockwave instead.
"What the-!" Ace shouted as the thunderous roar of a Sonic Rainboom assaulted his ears, making the trees of the orchard sway as the shockwave passed.
When it was all over, Ace took to air the air, desperately trying to find the pony who pulled off the Rainboom. "I've never seen a Rainboom like that…" Dan remarked, scanning the sky for any Pegasai that could've been flying around.
When no pony was to be found, Ace sighed heavily and shook his head. "Weird…" He turned towards Ponyville in the distance and narrowed his eyes. "Maybe somepony knows who cracked off that Rainboom…"
Yesterday, 1:16pm

Ace flew into town, landing gracefully outside Sugar Cube Corner. Courtly nodding at all the ponies that waved or said hello as he landed, he entered the Ponyville eatery, his eyes scanning the visitors of the restaurant.
"Let's see…" Ace thought to himself. "Could it have been that guy in the corner? Nah…too old…" He looked around some more. "That mare over there? Hmmm, no. Her colors don't match the colors of the Rainboom I saw…" Dan paused his train of thought, walking in and sitting down in a booth. "But then again, my Rainboom only matches my eyes… Gah, focus Ace! What about Derpy over there? The Raiboom was partly grey. Wha…no! What am I thinking?"
Ace face-hooved quickly before finally looking over at the last booth. "Hey look… It's Lightning Flash and…" He paused. "I've never met her before…"
Ace quickly left the booth he was sitting in and trotted over to the table Lightning Flash and the unknown mare were sitting, eating ice cream.
"Hey, Lightning!" Ace said cheerfully as he approached the table. "Turning the other cheek work out okay for you?"
"Oh, hey Ace…" Flash looked shocked at Ace's sudden appearance. "Um, yeah. I'm fine, thanks for asking." Flash gave an awkward smile, while the mare looked up from her ice cream and said nothing; staring at Dan with what looked like contempt.
"I just wanted to say again for hitting you…" Ace shook his head. "RD was in trouble, and I over-reacted…"
"No, no, Ace…" Lighting held up a hoof. "No need to apologize; I get it."
The mare who looked a lot like Flash widened her eyes and glared at Flash in a confused manner. Flash just looked at her and shrugged.
"Good!" Ace smiled and nodded. "So, did any of you see that Rainboom outside?"
Flash and the mare exchanged looks before Flash smiled awkwardly and shook his head, "Oh yeah! I saw it! It was a blue and grey one, right?"
"Yeah…" Ace narrowed his eyes. "Do you or your friend here know who-"
The mare suddenly jumped up from the booth and took to the air, clashing her head with Ace's. "Why do you hate my brother, Ace?"
"B-brother?" Ace stammered. "I thought you two looked alike…"
"Don't change the subject, Ace!" The mare advanced on the musical stallion. "The name's Star Flash, and I'm his older sister…and YOU…" She pressed her head harder on his and she flew in the air. "Have some explaining to do!"
Ace pushed the mare off him and shook his head, taken aback. "Jeez…" He kept to the ground as he looked up at the fuming mare, while Lightning Flash just tried to hide himself in the booth they were sitting in, trying to be invisible from the onlookers in the shop.
"Why in Equestria would you come to the conclusion that I hate Lightning Flash?" Ace shook his head in confusion. "He's awesome! And one of my good friends here in Ponyville!"

"Don't give me that, mister too-popular-for-others!" Star growled. "He told me all about how you could really care less about him and his feelings!"
Ace gasped and stepped back, "What!" He looked over at Lightning. "Dude, do you really feel that way?"
Lightning remained silent, slowly turning his head down to his ice cream.
"You couldn't be farther from the truth!" Ace whipped his head around to face Lightning's sister again. "I consider Lightning a friend! An ally!"
"Don't give me that!" Star Flash barked back. "I bet you couldn't win against him now! Because I'll tell you something else, mister curious! That Rainboom you saw…" She pointed a hoof outside. "Was Lightning's!
A very audible gasp was heard throughout the store as this was announced. Lightning again tried to make himself as unnoticeable as possible, but this proved ineffective; almost everypony was looking at him with widened eyes.
Ace didn't join in on the gasp; he just opened his mouth a little in surprise. He turned his head towards Lightning again and said, "Is this true?"
Lightning was looking back at Ace this time, a determined look on his face. "Yes." Another gasp from the ponies around the store was heard as Lightning got up, sighed, and trotted up to Ace. "It was mine… I am the third pony ever to pull it off."
Ace cocked his head in a confused manner and, with slight shock and confusion in his voice, said, "Well, why didn't you crack one off when we were racing, brony! You could've won!"
Lightning shrugged and looked down, "I…I didn't want to take the spotlight away from you and Rainbow Dash… I was afraid you wouldn't like me anymore as a friend and…" He moved his head from side to side. "That Rainbow Dash would fire me if I beat you…"
Ace just shook his head, chuckled, and smiled. "Dude, that couldn't be farther from the truth! RD and I, if anything, would respect you more! She would promote you, not fire you!" He put a hoof on Lightning's shoulder, which made the still uneasy Star Flash on edge a little. "You didn't have to cheat, man!" Ace sniffed. "And frankly, I'm a little…hurt…that you thought those things…"
Ace removed his hoof and frowned. Lightning widened his eyes with concern. "I'm sorry, Ace. I guess I just over-reacted…"
There was silence between the two stallions in the shop for a while. The only sounds that were heard were the whispers of some of the onlookers and the steady beating of Star Flash's wings as she remained airborne; her anger at Ace had become a sense of pity.

"Tell you what, though…"
Lightning Flash and Star Flash looked up at Ace as he spoke up again.
He smiled. "You. Me. Sweet Apple Acres. A rematch, sprint race to see who has the faster Rainboom!" He extended his hoof towards Lightning Flash. "From one end of the orchard to the other. Whatdya say?"
Lightning didn't even have to think. He clenched hooves with Ace before nodded and smirking. "Now you'll see what I'm really capable of!"
Yesterday, 1:16pm

A half an hour later found Ace and Lightning Flash standing, at the ready, on the cloud from earlier overlooking Sweet Apple Acres.
As Lightning snapped on his goggles, he looked over at Ace. "You sure you're up for this? You've only managed to do your Rainboom twice."
"I think I'm ready!" Ace rose his voice so the wind wouldn't be an issue. "How many times have you done yours?"
"Five!"
"Five!" Ace cocked an eye and took on a worried look. "Man, I'm bucked…"
"Shouldn't have accepted my sister's challenge, then!" Lightning smirked as he again readied himself.
"By the way…" Ace yelled above the wind-chill. "Has she always been like that?"
"Always been like what, Ace?"
Dan quickly covered his mouth with a hoof when his sister rose up in front of them with a green flag in her hoof.
"N-nothing…" Ace sweated awkwardly. "I didn't say anything…"
Lightning Flash snickered, and Star Flash just rolled her eyes.
"Alright, now I'm trusting both of you to play nice." She pointed at each stallion as they feigned starting stances. "This is a standard Rainboom sprint race. The objective is to achieve the Sonic Rainboom and see whose is faster. Whoever can race across the orchard and cross the fence on the other side while in Rainboom state first is the winner!" She narrowed her eyes and smiled.
"Are you ready!" She barked.
"Right on!" Ace and Lightning Flash yelled in sync.
"On your marks!"
Both stallions raised their haunches in preparation for takeoff.
"Get set!"
Both of the stallions started fluttering their wings rapidly.
"GO!"
In an instant, both stallions were off, leaving nothing but an intense gust of wind that threw Star Flash off of her flight pattern a little.
Both stallions were neck and neck as they rocketed over the orchard, the sonic boom cones slowly forming around each of them. Their eyes watering, and hooves stretched outward, both Pegasai strained to see ahead through the tears that were streaming down their faces from the wind.
A thunderous sonic boom shattered the skyline as they rocketed by, breaking the sound barrier as they did.
Color started to form around each of them; from Ace, a brilliant gold. From Lightning Flash, an electric blue and a pulsing grey.
In an instant, the color exploded around both of them, leaving not one, but two, shockwaves of color as they zoomed ahead.
"AAAAAAHHHHH!" Both Pegasai were closing their eyes to avoid any damage the wind might cause. Ace finally had the courage to move his head and look down. The fence marking the other side of the orchard was fast approaching. A little too fast. They only had a few seconds to determine the winner.
Despite all of Ace's attempts to flap his wings faster and get ahead of Lightning Flash, it proved futile. Ace tired out and slipped a split second behind as they both crossed the fence.
Both Pegasai, being extremely exhausted, let the Rainbooms die. Then then spiraled down towards the ground and landed hard on the soft grass below.
Both stallions laid on the ground, a few meters apart, panting heavily and sweat permeating on their brows. It was a few minutes before Ace managed to work out a few words between gasps for air.
"Good…job, Lighting…Flash…" Ace said between pants. "You…won…"
Lightning smiled. "Not…by…a lot, dude…" He turned and tore off his goggles. "You…you almost…had me…"

"Hmhmhm…" Ace chuckled. "That I…did…"
Both stallions were staring up at the sky and the passing clouds. Ace didn't know what Lightning was thinking about; most likely his victory. But Ace was thinking again about how he would have to leave. How this would be the last race he would participate in in Equestria.
"Hey, thanks, Lightning…" Ace said suddenly.
"Thanks what?" Lightning said, looking over at him.
Ace turned and looked too. "Thanks for giving me such a good last race…"
"What do you mean?"
"I'm leaving Flash…" Ace turned his head back to the clouds.
"What? Why?"
"I…I just am…" Ace sighed. "Celestia…she wants me to go to the zebra nation, thousands of miles away, as an envoy to prevent war…" He turned back to Lightning. "You understand right?"
"Oh, yeah. Yeah." He nodded. "Because of that freak Anansi, right?"
"Heh…" Ace exhaled. "Pretty much…"
They were both silent again for a while before Ace reached a hoof over to Lightning. "Thanks for being such a great friend, brony."
Lightning smiled, "Likewise, dude…"
"Brohoof?" Ace asked, smiling.
Lightning obliged and slammed his hoof onto his. "Brohoof…"