Not necessarily. 'Reindeer' could be purely imaginative or inspired by real-life but with significant alterations. It really varies depending on the context and the author's intention.
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.
There was a novel called " Encountering a Deer Around the Corner " that had been recommended many times. It was a Doujinshi novel written by the author, Nine Dinosaur Eggs. Although there is no specific plot introduction, this novel may meet your needs for a reindeer sadistic novel adaptation. Other than that, the other search results did not provide any other relevant recommendation information.
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.