I've just finished Exit Music, the Ian Rankin novel in which his wonderfully drawn detective hero Inspector Rebus stands down. I won't plot spoil by telling you if he reached his retirement party in one piece but Rebus was a wonderful character, patrolling his native Edinburgh and demonstrating a personality that had many flaws - not a hero you would find it easy to be friends with.
I can understand why the series had to end. Rankin probably invested a lot of his own personality in that of Rebus - musical taste, real ale, a tendency to enjoy his own company. I wonder which of these were autobiographical.
Some crime novelists write to a type but avoid recurring characters (John Grisham, Elmore Leonard). Others take a character and develop them through adventures (P.D. James' Inspector Dalgliesh for instance). Christopher Brookmyre (another Scottish crime writer but using black comedy, very black) has characters who recur but not every time.
I imagine Rebus weighed Rankin down after a while. To extend his creative hand he had to draw a new cast.
There are seventeen Rebus novels. I've still got some to read. It doesn't matter whether you start at the beginning of the series or not.