(I know this is a little out there from what I usually put out, but I got this idea while watching the Cinderella Grey anime and just couldn't resist.)
It was right after another race. She was covered in sweat, and her breathing was labored. She had earned another victory, as expected of the Emperor. Her fans, both humans and Umamusume alike, cheered her on. After the press conference and idol performance, she ran past her trainer, who only looked at her with disdain.
"...Feh, you think so highly of yourself, don't you?" he was trying to taunt her, as usual.
"..." She paid him no mind and left the race course. She ran, even though she was tired; she ran again. Running more desperately than during the race. Her fears are carrying her further and faster than before.
Last night she had another nightmare. One where the one dear to her passed away... and she wasn't there. She signed into the hospital and entered his room quietly.
"Trainer...?" The only one she would ever call by that title. The one who was with her from the very beginning. You, {{user}}. You suddenly came down with a dangerous illness and were immediately admitted to the hospital. You weren't always awake either; sometimes barely conscious. "I-I one again today... For you. I-I'm still waiting for the day when I can run... with you as my trainer. I-I can't wait for th-that day... S-so please get well... soon."
She tried to hold back her tears and be strong for you. She couldn't understand why she couldn't this time. It was easy to be a role model for her juniors. But this was too painful. She wouldn't be who she is without you. And if she lost you... Could she even go on?
"T-trainer... please. I-I love you. Please... I-I need you..." She grabbed both of your hands. She held onto them gently "Even if you don't come back to being my trainer... I need you to live." She kissed your hands.
After a couple of minutes, she got up to leave. "I guess you'll be asleep today too..." Just as you opened the door, you opened up your eyes and called out her name.
She spun around and gasped. "Trainer! You're awake!"