Who's your pick to sit on iron throne? Care to make it interesting?

No, that’s not a spoiler. It’s the collective conjecture of fans who are wagering on who will come out on top when the blockbuster HBO series comes to an end after an eight-season run.

While experts say they do not know of any strictly legal means to bet on “Game of Thrones” in the United States, there has been plenty of offshore and European wagering that suggests what fans and bettors — including some who claim to have inside information — believe will happen this Sunday.

Betting lines may change before the final episode airs, subject to fan whimsy or whether more plot details leak. And some bookmakers have been pulling back, no longer willing to offer odds, given how much information about the finale already appears to be circulating.

It has been one year since the landmark Supreme Court ruling that allowed states to legalize full-scale sports betting and take a piece of a $150 billion-a-year business that for years had been largely limited to the black market and Nevada.

Fan fever over the final season of “Game of Thrones” has yielded a glimpse of the sort of market that could exist for entertainment betting. Online sites that have taken advantage of the ruling to offer sports wagers are eager to make markets for other pop-culture bets that aren’t about sports, especially entertainment wagers.

“Fandom is universal, whether it be for a sports team or a television phenomenon like ‘Game of Thrones,’ and America is on the verge of an experiential evolution in how consumers will engage with their favorite content,” said Jamie Shea, head of digital sportsbook operations for DraftKings, one of the major legal online betting platforms in the United States.

Yet “Game of Thrones” has also shown just how hard it may be to have wagering on scripted Hollywood productions that isn’t plagued by leaks, and the betting markets’ version of insider trading.

Plot twists, denouements and sometimes an entire episode can seep out beforehand, making for markets that unfairly favor those in the know at the expense of fans and aficionados putting down money based on their hunches or their own studied analysis of what might lie ahead.

Despite a great deal of effort by HBO to keep a lid on things, key details of recent “Game of Thrones” episodes appear to have dribbled out ahead of time.

Anonymous leakers on Reddit, for example, forecast that Daenerys Targaryen would kill Lord Varys, and one claiming to have had a relative working on the show accurately predicted that Arya would leap toward the Night King and slay him just as he was about to kill Bran.

One television provider, DirecTV, even dropped this season’s premiere to some customers hours before its scheduled airtime, leading to complaints from offshore betting sites that they lost money to sharpies who rushed to place bets on plot details from the first episode before the window for betting closed.

Some employees at streaming services and television providers that broadcast the show in more than 150 other countries also have a legitimate need to review episodes before putting them on the air. The show is typically sent out to them about 24 hours before its 9 p.m. Eastern Time Sunday slot, thus creating at least the potential for someone to place a well-informed wager beforehand.

Driven in part by comments an HBO executive made at a Pennsylvania college in 2017, some fans have speculated that HBO filmed multiple endings for the finale, ensuring that no one really knows for sure what will happen.

Last year, Emilia Clarke, who plays Daenerys, seemed to confirm the strategy, telling The Hollywood Reporter that there were “lots of different endings that could happen; I think we’re doing all of them and we aren’t being told which is actually what’s going to happen.”

In turn, some skeptics believe that all of that might just be misdirection from HBO to keep people from believing the inevitable leaks.

For now, the heavy favorite to rule Westeros is Bran, aka the Three-Eyed Raven, who is played by Isaac Hempstead Wright. Bran did not appear in last Sunday’s episode, unless you are among those who believe he “warged” into the horse that Arya rode at the end.

The closest to him in betting odds is Sansa, followed well behind by Gendry, Jon and Tyrion. After her deranged bout of pyromania, Daenerys has slipped way back. (Though she is heavily favored to die on Sunday, probably by the hand of Jon, her nephew and lover.)

As of this writing, the line for Bran to rule Westeros stands at -450 at one major offshore betting site. That means that for every $450 bet, the profit for a win would be $100. It is equivalent to 2-to-9 odds, meaning a lot of bettors are pretty certain Bran will sit on the throne.

Some bookmakers have cited suspicious patterns of betting, especially on Bran prevailing at the end. Last week, Irish bookmaker BoyleSports suspended wagers after the odds on Bran shortened from 2-to-1 (which implies about a 33 percent probability of winning) to 1-to-4 (an 80 percent implied probability of winning) in the space of just two weeks.

Paddy Power, a large bookmaker in the United Kingdom and Ireland that had been offering odds on the show’s final season since August, has stopped taking bets, too.

“At the moment we’re not taking bets at Paddy Power because, with the final episode approaching, we’re conscious that leaks are possible, and we’d be keen to protect the market and also avoid any huge spoilers heading into the conclusion of the biggest TV show maybe ever,” said a spokeswoman, Amy Jones.

She said “Game of Thrones” has generated the most betting Paddy Power has ever seen for anything on television, excluding the hugely popular Eurovision Song Contest.

Concern about leaks and inside information explains why fans haven’t been able to place bets on the show on legal online wagering platforms in the United States.

“The risk of a breach in the integrity of the betting is too high for regulators to feel comfortable with that,” said Jennifer Roberts, associate director of the International Center for Gaming Regulation at the University of Nevada, Las Vegas.

In Nevada, for example, state gaming rules place anything other than sanctioned professional or collegiate athletic contests into a category called “other events.” Wagering on those events must be approved by Nevada’s gaming control board, and only if the event meets seven criteria, including that the outcome “would be generated by a reliable and independent process.”

Several of Mississippi’s 23 regulated sportsbook operators asked state officials to allow them to offer wagers on “Game of Thrones,” but were told no. The state takes a dim view of entertainment wagers generally, said Ed Wong, an official with the Mississippi Gaming Commission.

“On top of that, because it’s a scripted event and there’s no telling how many people know the outcome, it creates the possibility of unfair wagering,” Wong said.