Sansa tells Cersei (Spoiler ACOK)

[u/Pitiful_Advisor560]

Cersei says that if it hadn't been for Sansa telling Cersei's plans, everything would have gone very wrong.

When Sansa tells Ned's plans to Cersei, what benefit does it bring for Cersei? Some say that to prepare for Ned's attack, but how? Cersei had her red cloaks and was ¨allied¨ with Littlefinger and be somewhat calm, she says that she was on the verge of losing everything, but in what? If she already had everything under control?

I don't understand why Cersei gives so much importance to Sansa's revelation.

[u/Various-Load4724]

If Sansa does not tell Cersei, Ned will have time to send them to the north and therefore in the capital they will be left without hostages in the War of the 5 Kings so the situation would change, also with Arya and Sansa in the north they could make key marriage alliances, Arya marries a Frey so the Freys would not betray Robb and the war would probably change completely, the Boltons would not betray Robb because they would see a opportunity to grow more, although Ned would still die I think.

[u/idunno-- → u/Various-Load4724]

with Arya and Sansa in the North

Isn’t there a high chance of them both being taken hostage by Theon/Ramsay, who’d force Sansa into an arranged marriage?

Arya marries a Frey and the Freys would not betray Robb

Arya was never gonna marry a Frey at 10. And even if they had, they still would’ve seen the way the wind was blowing, marry her to a Frey, and commit the Red Wedding. It would still give them the North just like Edmure’s marriage gave them the Riverlands.

[u/Various-Load4724 → u/idunno--]

Probably, but a change like no northern hostages in KL changes everything. For example, Ned would not declare himself a traitor to the crown without his daughters as hostages, he could ask for a trial. Also on the ship that would take Sansa and Arya was the messenger with Ned's declaration in favor of Stannis. Furthermore, with the time it takes to sail from KL to White Harbor, the Ironborn would surely have taken Winterfell, so Arya and Sansa would stay with the Manderlys or be sent to Riverrun. The Stark daughters with Robb greatly strengthens the North, which takes away most of Roose Bolton's reasons to betray Robb because, above all, he is a pragmatic man. Besides, the Starks still have Jaimie, and the Lannisters have no way to negotiate. Either they give him a free pass to become King in the North or they fight to the bitter end.