a lil bit of lore:
Princess Luna had to banish her sister on the Sun for 1000 years

Luna doesn't have enough power to hold the sun on the sky for long enough because Celestia being in her nightmare form (it's not a Day Breaker but I don't have a name for her yet eeeee like Supernova or smth???) weakens Luna's connection with the sun (and also Luna holds less magic power than Celestia in general)

what's more Nightmare Celestia cursed Luna's ponies to be "the creatures of the darkness where you belong", turning them into Bat Ponies.

most of the ponies in Equestria are bat ponies.
Pegasy Unicorns and Earth ponies only comes from ancient pure blood families like Apples, Pies, Glimmers, etc
some as Rainbow and Rarity mostly look as regular pegasys and unicorn but they can hold trates of the bat ponies (fangs, ears, sometimes wings)
Bat ponies and the hybrids don't feel good enough during daytime (their eyes works so much better in the dark, they flies faster during night time and prefer lower temperature) and that's another reason why Princess Luna has to hold moon at the sky longer than sun

Apple Jack

• She puts flowers in her mane in the memory of her mother. In this AU Pear Butter is a very cool genetic. She died when Apple Bloom turns 5 and Apple Jack (who just turned 15) left absolutely heart broken. However this tragedy made Apple siblings much stronger and they've become closer than ever. That's when Apple Jack finally gets her cutie mark, representing her bond with apple family (three apples represent Apple Bloom, Apple Jack and Big Mac)
• Apple Jack is one of the ponies who doesn't really enjoy Luna's reign mostly because she is a farmer and it's hard for her to take care of the various apple trees during longer night time.
• The Apple family is VERY conservative they are one of the very few families in Equestria who still grows original sorts apples (and other crops), including a super rare Zap Apples and that need extra care due the lack of sunlight.
• one of the Apple family ancestors happened to be the leader of the earth ponies rebellion that happened in the first years of Luna's reign. Luna's spirit was broken after she had to banish her sister and things didn't go very well in her kingdom. Hundred of angered ponies led by the "iron mare" Red Delicious broke into the Castle of the two Sisters. The guards didn't even try to stop them. When ponies entered the throne room they saw The Princess of darkness, crying over her sister's broken throne. The room was filled with blooming Sunflowers, favorite flowers of Celestia. Then Luna turned to them and she spoke to them as a princess and they saw the power she holds and they realized she can destroy them all with a single spell. But she didn't. Red Delicious who was determined to fight "the princess of darkness" till the end finally saw the real Luna and she wasn't scared or angry anymore but started to feel the compassion for her.
• Red Delicious herself helped Luna to make a plan on defeating hunger. Ponies were starving due the lack of crops and Red Delicious worked hard alongside with Luna to invent plants that would be able to grow effectively in the dark on the shortest time. Ponyville became the first night farmers city (very close to the Castle of the two sisters).

Rainbow Dash

• Her full name is Rainbow Stormcloud Dash.
• Her mother and father are both pegasy and her grand grand father is a hybrid bat pony (she likes him sooo much he is super cool) However, she doesn't have any trates of bat pony except of the ability to see in the dark and flying at night.
• Rainbow mane in different varieties is a very rare gene that only exists in her blood line a very long time ago one of her ancestors tried to save his friend from a dragon and flied so fast he broke the laws of physics and a Sonic Rainboom happened. After that his mane turned rainbow colored. Pegasus with a rainbow mane was born once in a generation since then but a very few of them were able to perform a Sonic Rainboom.
• Rainbow Dash is the first pegasus in Equestria history who was able to perform the Nocturnal Rainboom.
• Her dream is to become a Shadow Bolt. They are the best flyers in Equestria!!! And most of them are bat ponies because it's hard for a pegasus to perform bat's tricks. Not for Rainbow though!