The Rainboom

After dealing with the disbelief, congratulations, etc from the ponies gathered to watch, the sun had already set. Only one pony remained to be seen.

“Princess Twilight,” Dash said, bowing.

“Dash, I went over this with your mother. Please, call me Twilight,” the mare responded.

“O-Of course,” Dash said. The pair began to walk, Twilight leading the stallion in one direction. “Is... is there something you wanted, Twilight?”

“Dash, do you know what color your eyes are?”

This question caught Dash off guard. He had been told that his eyes were green when he was born, but now...

“No, I don’t.”

“That’s what I thought,” Twilight replied. “Tell me, how did you do the sonic rainboom? Rainbow Dash is the only other pony to have done one - ever.”

“Well, this is going to sound crazy, but-“ Was Dash really going to tell her this? Princess Twilight Sparkle, Ruler of Equestria? “-but I... I hear a voice when I’m doing it. It just... it’s kinda like a mentor, I guess.”

“Ah. And tell me, does the voice sound anything like this?” Twilight’s horn glowed, and a moment later, Dash heard the exact voice he had been hearing. “-20 percent cooler.”

Dash gaped. “How- how did you-“

“That voice,” Twilight said. “Was none other than Rainbow Dash herself.”

“So my grandmother has been... giving me advice from the dead?”

“I don’t think so. You see, I have reason to believe - which I will tell you shortly - that your grandmother became the spirit of the rainboom. Even I don’t know how it works, but I still firmly believe this.”

Dash thought for a moment. It did make sense, didn’t it? Maybe. Then what- “You said that you had ‘reason to believe’ this. What was that reason?”

Twilight smiled. “Right on time.” Dash turned forwards, and realized that they were beside Ponyville’s lake. “Tell me, Dash - what color are your eyes?”

Dash blinked for a moment, staring at the moonlit water. He slowly walked towards it, and when he reached he edge, looked down.

Staring back at him was a young stallion with a messy mane and shocking rainbow eyes.

“W... What?” Dash said, confused. “Why...”

“This is my reasoning.” The Princess’s voice coming up behind him made Dash jump. “When the element of loyalty did her... last rainboom, the rainbow in the sky disappeared to most. Being clairvoyant, I was able to see where it really went.” Twilight turned towards Dash and laid a hoof on his chest. “It entered you, Dash Smith. The spirit of the rainboom, and Rainbow Dash, became a part of you - and took its form in the color of your eyes.”