I don't expect we'll see the wave of joyous reactions that greeted the death of King Joffrey earlier this season, but I'd be surprised if anyone spends much time grieving Lysa Arryn after tonight's "Mockingbird." In her brief appearances in Game of Thrones, Catelyn Stark's younger sister was unpleasant at best and psychotic at worst. She imprisoned Tyrion Lannister for a crime he didn't commit, refused to support her nephew Robb Stark during the War of the Five Kings, and poisoned her own husband, setting the entirety of the series into motion. (And yes, yes, there was the whole "breastfeeding an 8-year-old" thing.)

But as hard as it was to like Lysa, there's something heartbreaking about her death at the hands of Littlefinger at the end of "Mockingbird." "You want her? This empty-headed child?" Lysa cries, shortly after she sees Littlefinger kissing Sansa. "She's just like her mother. She'll never love you. I lied for you. I killed for you. Why did you bring her here? Why?"

As last words go, those are particularly painful ones — but they're nowhere near as bad as her final moments, when Littlefinger cruelly reveals that he never loved her before pushing her to her death. Despite his obvious love for her sister, Lysa spent her entire life pining for Littlefinger, placing her trust, her safety, and her happiness in his hands. He swears he loves her on all the gods and on his own life. And now, just days after marrying Lysa, Littlefinger doesn't just betray her — he twists the knife enough to ensure that her final moments alive are as painful as possible.

"Mockingbird" was a busy hour of Game of Thrones, spending time as far north as the Wall and as far south as Mereen — but every story in the episode could be boiled down to a matter of trust. Lysa could hardly have pinned her hopes and dreams to a less reliable partner, but Westeros isn't a world that should be braved alone, which raises the question: How do you know who can be trusted? It's a question that Daenerys is grappling with, as she invites Daario into her bed (and receives a subsequent dressing-down from Jorah Mormont). It's a subject of debate between Brienne and Podrick, who learn that Arya is alive after confiding in our old friend Hot Pie. It's an ongoing struggle between Arya and the Hound, whose mutual survival depends on an uneasy alliance that grows stronger in "Mockingbird."

And it is, quite literally, a life-or-death problem for Tyrion, who is desperately searching for someone to serve as his champion in his trial by combat. When faced with a similar situation in Game of Thrones' first season, Tyrion chose his brother Jaime; when Lysa refused to wait until Jaime arrived, Tyrion settled for an unscrupulous sellsword named Bronn. "Mockingbird" finds Tyrion in the same situation, and he chooses the same two men to defend him. They both turn him down.

The Jaime who meets Tyrion in the dungeon in "Mockingbird" is a very different man from the cocky, brutally efficient man who fought Ned Stark in the streets in season one — and not just because he no longer has his sword hand. The Lannister family has been ripped apart due to Joffrey's death, and Jaime is at the center of it, torn between his brotherly love for Tyrion, his romantic love for Cersei, and his filial duty to Tywin. There's a long, awkward beat as Jaime blames his sword hand for his inability to defend Tyrion, but neither man openly acknowledges the likely truth: Even if Jaime were 100 percent healthy, it's extremely unlikely that he'd oppose his father and sister in such a public and humiliating manner.

That leaves Bronn, who has always been defined by his utter lack of interest in honor — which is why Tyrion knows something is fishy when Bronn shows up in an uncharacteristically spiffy new outfit. Tyrion was always smarter than Cersei, but he can't outmaneuver her from inside a jail cell, and she's found something that Tyrion can't offer: A lordship, with the likely possibility of a castle, due to a convenient marriage with the dimwitted Lollys Stokeworth.

Bronn has always been cheerfully upfront about his untrustworthiness, which made it hard not to trust him. But while he's remained more loyal than Tyrion's former allies, like Varys and Shae, his friendship also has its limits. "One misstep and I'm dead. Why should I risk it?" Bronn asks Tyrion. "I'm your friend. And when have you ever risked your life for me? I like you. I just like myself more."

By all accounts — including his own — that should leave Tyrion to personally engage in what would presumably be a one-sided fight with Gregor "The Mountain" Clegane. "Careful. I'm the last friend you've got," warned Jaime earlier in the episode — but relief comes from an unexpected source when Oberyn Martell enters the cell and volunteers to stand as Tyrion's champion. Trust can be built on any number of foundations, but Tyrion and Oberyn have a particularly unique one: Their shared enthusiasm for dead Lannisters. Oberyn is still hungry for justice for his dead sister, and the trial by combat gives him both the legal excuse and the moral high ground.

That sets the stage for what should be a fascinating, emotionally charged battle in the next episode of Game of Thrones — a battle which will have significant implications for all of Westeros. All legal systems are built, to some degree, on trust: The ability to use reason and rhetoric to determine the real story, and the wisdom and intellect of a judge to determine a fair sentence. But Game of Thrones' system of trial by combat takes things to the next level. The people of Westeros actually believe that the gods determine the outcome of those battles, which means that Cersei can stack the deck with an acknowledged rapist and murderer like the Mountain.

But the idea of justice remains an open question in Game of Thrones. Are there penalties for the evils these characters commit — and if so, what form will they take? Is Oberyn merely a brave and dangerous sword fighter who's in the right place at the right time — or is he the personification of justice, sent to avenge a long-overdue wrong on the monster who committed it?

Whatever the truth, Oberyn clearly believes that he's capable of delivering the payback the Mountain so clearly deserves. When Tyrion remarks that Oberyn has come to the wrong place for justice — a moment that formed the backbone of many trailers for Game of Thrones' fourth season — Oberyn parries him right back: "I've come to the perfect place." And whatever the reality of justice in Westeros, it's hard not to trust someone with that kind of conviction.

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