Celestia, Luna, and Cadence trotted up to her out of the radiant gloom.
The sun princess came to a halt in front of Rainbow Dash, eyes dark with all the regret, pain, and loss accumulated during a lifetime that nearly spanned forever. And now this. Her horn glowed softly: Mike appeared, a half eaten windfall apple in his mouth, which he dropped in surprise so that it fell, rolling away into the darkness that surrounded them.
"We have found that a conflict has arisen." Tail and neck arched, the princess of the sun lightly cantered gracefully around Rainbow. Rainbow dropped her head, sidling away in her unwillingness to meet those beautiful, sad eyes. Celestia continued, "You hurt Mike, becoming euphoric from his pain and humiliation, didn't you?"
Rainbow's ears drooped as she suddenly became very, very interested in her front hooves. Finally, "Yes, your Majesty." she mumbled, trying not to cry or let her back legs collapse out from under her.
Celestia halted, raised her shining head and studied the wary Mike, who attempted to back away from her, eyes rolling nervously, only to blunder over his own hooves. Cadence trotted up to him, lightly gripping his sweating neck between her chin and chest in the equine answer to a human hug. He relaxed, slightly as Celestia serenely added, "Mike, we are sorry we even allowed Rainbow Dash to pursue her dreams in your world, tipping the balance in the wrong direction and causing harm. As an apology, we can send you back with no memory of this having ever happened, if you so wish."
Shivering, Mike shook his head.
Cadence whispered in his ear as she led him away into the dark glow between the stars, "We really meant no harm. Can you forgive us our folly? Is our world really so terrible? Just say the word and we'll send you home as if it never happened."
He shook his head again.
Luna stepped forward, dark mane flowing in the starwind. She arched her neck as she watched Celestia lead Mike away into the darkness between the world, their rapidly receding hoofbeats echoing among the solar tides. She then looked down on the much shorter Rainbow Dash, "Harsh as it seems, we sisters have spoken to Captain Spitfire of the Wonderbolts.
Rainbow's wings stiffened and then drooped. She knew what was coming, but needing to hear it anyway even if it hurt.
"It is agreed, you're no longer fit to be a Wonderbolt. Nor will you ever be again – balance must be restored."
Rainbow staggered as if struck, but in doing what she'd done to a fellow flier, even if he had no wings of his own… she'd disappointed her Commander, no… she'd disappointed everyone. Her punishment was just.
Cadence who had returned alone from between the stars added, her voice cracking slightly, "I'm afraid you'll also have to choose between worlds. It's one or the other with no chance of ever returning."
The little Pegasus with the choppy, blackened rainbow mane and tail stood head down and trembling for what felt like forever.
Eventually she looked up, meeting Celestia's eyes, knowing her answer.