Oscar winner Jim Broadbent is checking off a crucial box on his respected British character actors bingo card, joining the cast of HBO’s Game of Thrones for the show’s seventh season in an as-yet unspecified role.

As is traditional for the long running show, details about Broadbent’s character have not been revealed except that the role is confirmed to be significant. Casting descriptions sent out in recent months for season 7 have been vague. Complicating things further, as George R.R. Martin still has not released the sixth book in the A Song Of Ice And Fire series, the show has now far-surpassed the books on which it is based. That makes picking out which of the series’ multitudinous characters Broadbent might play difficult.

But of course that doesn’t mean we can’t speculate, so here goes: In both the show and novels, one of the most important underlying concepts is the so-called prophecy of the prince that was promised, which predicts the return (or perhaps reincarnation) of a mythical hero who long ago saved the world from being overrun by the White Walkers during a particularly long, brutal winter. There are differening versions of the prophecy but all agree that the Prince comes from the Targaryan family line.

In the books, the most important and intriguing part of the prophecy coomes courtesy of Maester Aemon of the Night’s Watch, (himself a Targaryen), who in the fourth book of the series tells Samwell Tarley that “the dragon has three heads… but I am too old to be one of them. I should be with her, showing her the way, but my body has betrayed me.” As a result, the assumption among fans is that this means there will be three people who fulfill the prophecy, each riding their own dragon. The most popular candidates for the job, by the way, are Daenerys, who happens to have three dragons under her command, Jon Snow, and a third person I won’t spoil for non-book readers.

However, that scene never happened in the tv series. But with Samwell now at the Citadel learning to be a Maester and Jon Snow newly revealed as a Tagaryen himself, it’s a good opportunity to bring this aspect of the prophecy into the HBO show. Given Broadbent’s physicality, persona and prestigue, my bet is that he’s playing one of the Archmaesters and may end up delivering this crucial information to Samwell himself. But feel free to speculate on your own in comments.

The seven-episode seventh season of Game of Thrones will air next summer instead of the usual April launch date, thanks to a delayed production to allow filming during harsher winter conditions than would exist under the usual shooting schedule.