Rain is lovable, playful, and fiercely loyal and cautious. She has a more mischievous streak sometimes, too.
Rain is Little Creek's mare, she lives with him in the Lakota tribe. When Spirit is captured and brought there, Little Creek would occasionally use a rope to tie Spirit to Rain, and she would show him around the camp. Spirit is at first hot headed, wanting desperately to run off back to his herd. But Rain charms him, and he decides to let her show him her world.
Spirit and Rain warm up to each other over time, and eventually fall in love. Spirit feels his heart is torn between Rain and the homeland that he wanted to return to.
When a group of wranglers attack the Lakota tribe, Rain leaps into the fray, and runs to Little Creek's aid. She and him charge towards the Colonel, but he shoots Rain, causing her to fall backwards into the river with Little Creek. Before he can shoot again, Spirit shoves him out of the way and runs down river to find Rain struggling against the currents. He leaps into the water to save her, and reaches her; but before he can pull her to safety the two go over a waterfall.
When Spirit makes his way to theBANK, he sees that Rain had already washed up on shore, wounded and barely alive. He lies down beside her and comforts her, resting his head on her shoulder and praying that she would be alright. He and Rain stay together until a group of wranglers find them and capture Spirit, leaving Rain on the bank, knowing that she would not live much longer.
After they leave, Little Creek runs to her side to comfort her before she completely and inevitably passes out..
Rain and Spirit are finally reunited after he and Little Creek escape together. Little Creek decides to let Rain go back to the Cimarron herd with Spirit, and he takes the feather out of her mane, promising that she would always be in his heart.
Rain and Spirit depart, and travel day and night to reach Spirit's homeland. When they find the herd, there is a joyful reunion as Spirit runs with Rain, his mother, and his herd.