Copies of “Grey: Fifty Shades of Grey as Told by Christian” by British writer EL James are on display at a London bookstore. (Facundo Arrizabalaga/European Pressphoto Agency)

June 18 was Christian Grey’s birthday, and readers who have been desperate for the dreamy Mr. Grey to see them now are receiving the gift they’ve been waiting for. Others are just hoping they can survive the day without running into the megalomaniacal sociopath.

With 125 million copies of the “Fifty Shades” series in print, there are few readers who don’t know precisely how they feel about EL James’s juggernaut of a series and its hero, Christian — the twitching palm that launched a million fantasies.

However one feels about the series, there’s no denying that “Grey,” released worldwide Thursday, is a completist’s dream. It retells the story of “Fifty Shades of Grey” and the earliest section of “Fifty Shades Darker” from Christian’s perspective. It is a behemoth of a book, 557 pages of Ana and Christian’s fraught and at times unsettling love story, here made more unsettling by the truth that fans already know: Christian is not just dark and mysterious. He’s everything he warned Ana he was in the original book. He’s unquestionably “fifty shades of [expletive] up.”

With “Grey,” James sets out to explore those shades and explain Christian’s controlling tendencies, which had critics of the series questioning the health of Ana and Christian’s relationship and BDSM practitioners arguing that this couple provides a poor representation of the dominant/submissive lifestyle.

It is not every day that an author has a chance to recast a polarizing character, and James works hard to do that. The book is framed with emotional flashbacks to Christian’s youth, from his early years with a “crack whore” of a mother, abused by “her pimp,” to his later childhood, learning to be a part of the loving family that adopted him. Christian’s “nice” family is perhaps the strongest vestige of the “Twilight” fan fiction from which “Fifty Shades” was birthed, and the scenes with the Trevelyan-Greys make one wish this family were still adopting children.

But even with all this explanation, with the clear and well-trod defense of Christian, it’s difficult to understand him. Or rather, it’s difficult to understand why any woman in her right mind would take a chance on him. Where “Fifty Shades” readers could fill the mysterious blank slate of Mr. Grey with their own ideas of what he was thinking, in “Grey” the disturbing truth is revealed. Upon first meeting Ana, Christian must “repress [his] natural annoyance at [her] clumsiness.” When Ana vomits after drinking too much, he attempts to emotionally dominate her on the sidewalk outside the bar, thinking, “Let’s have some fun.” These moments slowly disappear as Ana changes him, teaching him to love, but it is difficult to forget what it is like to be inside “control-freak” Christian’s head.

What readers who dislike the series will find redundant about this new novel, readers who love the series will find thrilling. Indeed, it’s easy to imagine that James began here with the original manuscript of “Fifty Shades of Grey,” stripped out everything but the dialogue and rewrote it. The e-mail exchanges between Christian and Ana were by far the most entertaining and inspired part of the series, and they are repeated rather than expanded upon in “Grey.” The famed “contract” outlining the sexual relationship between them appears again, and readers fascinated by legal documents will be happy to see that Ana’s background check is here, as well. New scenes with Christian’s family and former lovers are perfunctory, but they will entertain curious “Fifty Shades” readers, as will the end, a rewarding look at Christian’s decision to toss caution to the wind, finally, and win Ana back.

But curious readers aren’t those for whom James is writing. She says so, dedicating the book to “those readers who asked . . . and asked . . . and asked . . . and asked for this.” She’s writing for the acolytes, and one imagines the truest of fans reading with fervor Ana’s dog-eared story in one hand, Christian’s in the other, finally, finally gaining access to his impenetrable mystery.

“Fifty Shades” fanatics might still struggle with “Grey,” however. There is none of the undeniably compulsive readability of “Fifty Shades” here. This new novel simply isn’t entertaining in the way the trilogy is from Ana’s perspective. Part of the fun of those books came from James’s ability to write to readers’ id without apology, but here she pulls her punches. Where Ana had bizarre quirks, a perplexing “inner goddess” who was an Olympic-caliber backflipper, and a general sense of naive wonder that lightened “Fifty Shades” and reminded readers not to take the story too seriously, there is none of that here. “Grey” is dark and unrelenting and far too serious, like Mr. Grey. No one can ever say that James does not understand her characters.

MacLean is a romance novelist and reviews romance for The Washington Post every month. For more books coverage, go to washingtonpost.com/books.