To make the reader's dreams come true. Original plots, realistic characters. Predictable plots often involving a god-like figure who solves everyone's problems. At the end, all the reader has to do is sigh with satisfaction. Characters are usually individuals and may act in unexpected ways as do real people.
Characters make major personality changes slowly and, sometimes, painfully.
Characters make major personality changes easily and quickly. It can sell immediately after publication or be ignored until many years after the author is dead. It can be tremendously successful for a short time and the author gets as wealthy as income taxes allow, then is forgotten just as fast.