If we consider a more general view, in some regions where reindeer are native, baby reindeer might be part of a herd managed by indigenous people. The cast (assuming you mean group) of baby reindeer would grow up learning from the older reindeer in the herd. They'd learn how to forage for lichens, which is a major part of their diet, and how to migrate to different areas depending on the season. Their real story could involve survival in harsh Arctic or sub - Arctic climates, dealing with snowstorms and limited food resources during the long winters.
One fact is that baby reindeer, called calves, are born in the spring. They are able to stand and walk within an hour of being born. Fiction might be that they are born with fully grown antlers, which is completely untrue. Calves are born without antlers, and they develop them as they grow older.
I'm not entirely sure. It might be a real story if it's based on someone's actual encounter with a baby reindeer in the wild or on a reindeer farm. However, it could also be a fictional story made up for entertainment, like in children's books or movies where baby reindeer are often depicted in magical or anthropomorphic ways.