“Only one Queen can survive, and I intend it to be me.”

This thrust of this final season of “Reign” has been, fittingly, the simmering rivalry between Mary (Adelaide Kane) and Elizabeth (Rachel Skarsten) as it edges toward the climax we know is coming. That the show has taken such time and care to explain these cousins’ divergent philosophies only adds to the chill when Elizabeth explains, yet again, that this is a Harry-Voldemort situation: Neither country is safe, and neither woman can truly live so long as they both survive. Elizabeth entered the show as a villain, threatening our beloved Mary, but the maturity with which she understands their mutually assured destruction is impossible not to find sympathetic. Heavy is the head, after all.

The rivalry between these two women became famous not just for its scope, but for its singularity: When else, in history, have two warring countries been led by two unmarried women — either of whom could upend the balance of power at any time? The episode begins with Mary’s devoted lover Gideon (Ben Geurens) reminding us, via Elizabeth, about they ways they’ve ascended, and how they diverge: Mary, crowned at six days old; Elizabeth, raised a bastard for most of her life — a Queen nobody anticipated.

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Perhaps it’s Elizabeth’s familiarity with that feeling of powerlessness that allows her to make the seemingly heartless decisions she must constantly make. We watched her cast aside her lover last season because, even in the midst of heartbreak and infatuation, she knew to choose self over country would be tantamount to suicide. This week, Mary is faced with a similar decision… And finds herself waffling.

While Elizabeth has been shown, on this show at least, to rule from well-honed instinct and intuition, Mary prefers — and urged her husband the Dauphin (Toby Regbo) at every turn — to mull things over with a variety of advisers. And while accepting advice from a smitten ex-English spy who wants to marry you isn’t necessarily one’s best choice, Gideon’s proposal — to abdicate and marry him, pledging fealty to Elizabeth — does have its temptations. Not least among them that it assures, as much as possible, Mary’s continued survival.

ben geurens adelaide kane gideon mary reign cw Neither can live while the other survives: The noose tightens on an intense Reign

In a twist, for those of us familiar with the “real” Mary’s romantic history, Mary and Gideon must perform the love they truly feel, so that her subjects find her desertion understandable and sympathetic. This leads to what may well be one of the last of “Reign”‘s signature upbeat dance sequences — and if it is to be the show’s final show of pure joy, Adelaide Kane’s palpable joy sells the moment (along with a stunning, glittery, fruit-patterned gown). Gideon’s sales pitch is indeed tempting, to a woman who has always clung to the simplest parts of her girlhood — snowball fights, boat rides, and that iconic twirl from the pilot episode.

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But we all know, and Mary likely does too, that this is too good to be true. When she finds out that the home Elizabeth has promised for her and Gideon is little more than a gilded birdcage, her face falls less with surprise than resignation. Her affair with Gideon was certainly reciprocal, but somewhere along the way he lost track of what was possible — Mary, who lived only five days without the responsibility of a crown, always knew this wouldn’t end in a cottage with a commoner husband. The very words Gideon uses to convince her to abdicate — that she doesn’t have to win, or die, to win this conflict — only cement what Mary knows to be true: This conflict between women and nations truly can’t end until she or Elizabeth is dead.

Given where we know the real Mary’s life will take her, there is real pathos in Mary’s passionate refusal to commit to life in a virtual prison of Elizabeth’s making: She would be alive, perhaps, but at what cost? Gideon’s proposal, like their gleeful dance, feels like one final stop towards her inevitable downfall — but she doesn’t know that yet.

And in her defiance, we see the peculiarly admirable power she’s grown into over the course of this show: A woman willing to consider what her heart wants, who will occasionally indulge her humanity, but who ultimately will stand firm for what she believes in. And, after toying with the idea of running away, she has come to accept this means agreeing to a marriage that is also, effectively, a declaration of war.

It is unusual to enter the final season of a show like this with most of the viewing audience knowing the dire fate of its beloved protagonist. But that’s refreshed now that we know Mary herself is resigned to the inevitability of death, spelling out perhaps the thesis for the duration of this show:

“We all die, Gideon. The question is what we stood for while we lived.”

“Reign” airs Fridays at 8 p.m. ET/PT on The CW.

Posted by:Ann Foster

Writer and historian living on the Canadian prairies.