The Great Goddess, Calais, had four strong sons. Each one had immense powers, but they were always warring with one another. The eldest, Cedric, meaning chieftain, had the ability to make plants grow. During the time before his brothers came into their powers, he enjoyed making things spring up all over the place and during that time, the world had such an abundance of plants that the humans had to take swords to cut paths through the forests. He could also cause thunderstorms to come up quickly.
The second oldest son, Colin, meaning victor, controlled the heat and sweltering sun. He kept the earth in its prime, not actually growing and budding, but where it was full, green, and lush.
The third, Conan, meaning hound or wolf, caused the changing of the leaves from green to brilliant reds, oranges, and browns. He was responsible for the trees to bear their fruit and completely show the plant cycle. He also made the days shorter.
Finally, the youngest, Ciaran, meaning dark, caused for the hibernation of the plants his brothers loved. In most places in the world, he caused soft, white flakes to cover the land for this hibernation period.
The four brothers fought constantly because each one wanted to be in constant control of the Earth's plants and weather. Their fighting got so great and was spilling over into the human world that finally, their mother decided to step in to stop it.
Calais spoke to each son and discovered each one's point of view. She knew that once she passed her judgment, it was final. Her sons could not argue any more after her verdict. She thought long and hard about her decision. Finally, she decreed that each one of her sons would rule the earth for three months out of the year, roughly. She said that each one would have their time and then move to let the next rule. She also decided that the order of ruling would go according to the age. Cedric would go first, then Colin, then Conan, then Ciaran.
Over the years, this seemed to work rather nicely. Yes, there were times when it took longer for one to give up power, but as soon as it was brought to Calais' attention, she removed the son that was refusing to give up his throne and set the next one into place. Whenever it was time to trade off, the two brothers trading would have to do, one slowly giving his power to the other, so that none of the three not on the throne could work to overthrow the one on. It also allowed a slow transition between the new seasons.