What if, instead of Celestia ruling over day and Luna over night, there were four Alicorns who controlled the seasons? Well, this would happen *points to picture*
Vernia the spring Alicorn wears attire made out of stones that have been overgrown with vines to represent how in springtime plants and animals come to life over the dead earth. Her coat is the color of new grass and buds, while her mane is decorated with springtime blossoms. Her cutie mark is a stone shaped heart with vines creeping over it.
Agni is the summer alicorn. His crown & other accessories are made out of gold-lined metal plates were forged by a blazing fire and adorned by two gleaming rubies. His coat is a burnt color, representing what the fierce summer sun can do, and he has a mane of roaring flames. His cutie mark is a fiery sun.
Autumnia is the fall alicorn, with a coat of pale auburn and a light blonde mane that constantly shifts and blows like wind. Her attire is made up of leaves turned orange and red, accompanied by acorns that become ripe in the fall. Her wings are large and powerful, perfect for blowing leaves off of trees to make room for winter. Her cutie mark is a cluster of leaves being scattered by the breeze.
Glacia is the winter Alicorn. She is aloof and cold, with a coat in the same color of freshly fallen snow. Her mane is a cool blue and is swirling with snowflakes. Her attire is made out of sharp, crystalline ice structures that never melt, yet still feel cold to the touch. Her cutie mark is a large snowflake along with several smaller ones, all surrounded by cool north winds.