When Tyrion and Sansa reunite in Game of Thrones’ Season 8 premiere, their conversation begins by highlighting how far they’ve come since they last saw each other. After reminiscing about the good times of their marriage—remember when Joffrey died and we never saw each other again?!?!—Tyrion pivots the conversation toward the subject of Cersei, who has pledged to honor a truce and send troops to fight alongside our heroes in the war against the dead.

“You have every right to be fearful of my sister,” Tyrion says. “Nobody fears her more than I do. But I promise you’ll be safe.”

Sansa is stunned that he believes Cersei’s claims. (Rightfully so: Read that above sentence again. It’s a bananas thing to say!)

“I used to think you were the cleverest man alive,” Sansa says. She walks away without finishing the thought, but she doesn’t have to. We, too, once thought Tyrion was the cleverest person in Game of Thrones, because for years that assessment was correct. He followed his escape from the Vale thanks to trial by combat by saving his own life and Bronn’s life from the threat of the Stone Crows in the next episode with one of the best lines in the entire series:

“How do you want to die, Tyrion, son of Tywin?”

“In my own bed. At the age of 80. With a belly full of wine and a girl’s mouth around my cock.”

He convinces them not only to spare them, but also to provide safe passage to his father’s army. In Season 2, Tyrion saves King’s Landing in the Battle of Blackwater with the wildfire plan and an emotionally intelligent speech. That same season, Varys tells Tyrion that he is excellent at playing the game, and Tyrion says he’s always been good at problem-solving. He had a devious plan to figure out which member of the Small Council was snitching on him to Cersei. And when his father put him in charge of the sewage system at Casterly Rock, the drains never flowed better.

But the past few seasons, Tyrion’s drains have been clogged. Suddenly the wisest man in the realm has become kind of a moron. He gets kidnapped by Jorah after leaving Varys’s side in Volantis because he expects that nobody will recognize him. Tyrion fails upward into a gig as hand of the queen with Dany, and she leaves him in charge of Meereen. He promptly proposes a disastrous, paternalistic, and morally contemptuous truce with the masters of the slave cities despite fervent pleas from Missandei and Grey Worm not to trust them, and the slave cities betray them just as Grey Worm and Missandei predicted. Meereen is saved only when Dany returns with her dragons and Tyrion devises a plan to unscrew the situation. Later, Tyrion concocts the plan to bring a wight to King’s Landing—the strangest subplot in the entire series—because it’s the only way to bridge a truce with Cersei. Then, when that plan goes south, Tyrion tries to convince Dany not to fly north to save Jon and the rest of the mission. His batting average as Dany’s adviser is lower than Chris Davis’s. And not only is he acting stupider, but he believes stupider things. As he narrates a battle between the Unsullied and the Lannister forces at Casterly Rock in Season 7, Episode 3, he pitches Daenerys on why her forces will defeat Cersei’s.

“They will face the bulk of the Lannister forces,” Tyrion says. “They will be outnumbered. They will have less armor and fewer weapons. But my sister’s armies fight for her out of fear. The Unsullied army will be fighting for something greater. They will be fighting for freedom and the person who gave it to them. They will be fighting for you. That is why they will triumph.”

This very idealistic notion of combat is the opposite of the entire Thrones ethos. Compare that idealism to Season 1, when Bronn saves Tyrion’s life by winning the trial by combat, and then Lysa Arryn scolds Bronn because he did not fight with honor.

“No,” Bronn says, before gesturing toward the man he had just tossed out of the Moon Door. “But he did.”

That is the logic that makes George R.R. Martin’s stories special. It’s hard to imagine the Tyrion in Season 1, smiling at Bronn’s victory, listening to the Tyrion in Season 8. That Tyrion has forgotten this cold brutality—or worse, changed his mind despite all available evidence—takes some luster out of the show and wisdom out of his character. He may have had the sewers flowing well when he was younger, but these days he is full of shit.

Sansa smells it immediately in the Season 8 premiere. It’s worth looking again at just how bonkers Tyrion’s claim is:

“You have every right to be fearful of my sister,” Tyrion says. “Nobody fears her more than I do. But I promise you’ll be safe.”

First off, Tyrion’s “I promise you’ll be safe”—from a person he’s called the most murderous woman in the Seven Kingdoms—seems like a classic promise that cannot be kept. Second, plenty of people fear Cersei more than Tyrion does. Just one episode ago, Tyrion walked into Cersei’s chamber alone, dared her to tell the Mountain to kill him, and was promptly cut in half and became the quarter man. Wait, just kidding! He was fine! How he escaped that meeting with Cersei, and why Cersei did nothing to harm him, remains unclear.

That interaction was so sus that theories have developed around whether Tyrion has ulterior motives. Perhaps he saw that Cersei has a baby on the way and his heart softened for his family. Who among us doesn’t get a bit weepy when a baby is on the way? A story line in which Tyrion helps his own family wouldn’t be unforeseen. Dany called Tyrion out on his allegiances explicitly in Episode 4 last season, and Tyrion certainly had some misgivings after watching Lannister soldiers burn at the Loot Train Attack. But Tyrion making some backchannel arrangement once he found out Cersei was pregnant in the Season 7 finale wouldn’t explain why he’s just been stupid for a few seasons now—including going to see Cersei in the first place, since he didn’t know she was pregnant.

Another possibility is that he loves Dany. Look at how he’s staring at the door to her bedroom when Jon enters.

Perhaps Tyrion has feelings for his queen. It would explain why he has lost his head. (In the words of Robin Williams, a man has two heads but enough blood to run only one at a time.) Yet this, too, would feel hollow if Tyrion’s feels are shoehorned in with five episodes to go.

The most likely answer is that Tyrion is simply the most obvious example of a book character becoming thinner as a television character. Thrones condensed the final two seasons into a combined 13 episodes when the show probably could have stretched it to 20 (if not 30). Nobody has suffered from this concentration more than the master plotters—Tyrion, Varys, and Littlefinger—who went from seeming like marionette puppet-masters to guys who still love puppets but no longer have any strings connecting them to the wider world. George R.R. Martin has said his favorite character in the books is Tyrion, and it wouldn’t be surprising if he took extra thought when he wrote Tyrion’s chapters. The further the show strays from the books, the more treading water it does, and perhaps Tyrion is just the most glaring example after the travel gaps of Season 7.

Regardless of why, there’s no question Tyrion isn’t as sharp as he used to be, and that’s a shame. One of the masterstrokes of the early seasons of Thrones was these plotters understanding how the world works. Now, in the final season of the deadliest period of the deadliest TV show ever, Tyrion is guaranteeing safety to someone who knows well that nobody can protect her. Like Sansa, we’re not mad at Tyrion. We’re just disappointed.

Disclosure: HBO is an initial investor in The Ringer.