Miranda and Starlight
Miranda Stevens, a 10 year girl living in Montana with her grandparents, loves horses more than anything. When she accepts a dare from another classmate, Miranda finds herself in love with a jet black stallion, who she names Starlight.
From then on, Miranda will do to do almost anything to be with Starlight, she even tries save him when his owner wants to put him down, due to an serious injury. And with bond that Miranda has with Starlight, she won't let "her" horse die.
The 6 books are about Miranda who wants to own Starlight. And eventually... Well, I'll let you find out what happens when you read the great (I mean GREAT :) ) series.
It is one of my FAVORITE series (not just one of my favorite HORSE series!)