In the six weeks since the announcement that Ace Atkins would continue Robert B. Parker's Spenser, members of my Parker discussion list, Spenser's Sneakers, have warmed to the idea. Most recently, we've wondered how Atkins will write Spenser's longtime love, Susan Silverman Ph.D.
Many fans equate Susan with Parker's widow, Joan, and Joan has said (jokingly?) she would speak with Atkins about making more of a distinction between them. That aside, even if Parker did base Susan on Joan, Atkins can't see Joan the same way.
This branched out to the observation that Susan once played a vital role in the series. A three-book separation resolved in Spenser and Hawk rescuing Susan from her conveniently villainous lover. In the twenty-five years since then, the breakup has hardly been mentioned, and many readers have grown indifferent to the static relationship.
If Atkins can introduce something over which Spenser and Susan meaningfully fight, readers may invest in the relationship again. The fight doesn't have to break them up or persist for more than one book; it just has to highlight how they differ and why they are together despite those differences.