And his son and Arya did not disappoint him. Not a weak had passed since he received the news from Westerlands before what happened to House Frey in their castle spread around Westeros.
Edward was right to send his son and Arya to learn from the faceless men. The faceless men were the best assassins in the world, but they were costly. Although Edward could afford that price, he preferred to save the gold for something much important. Plus, Edward had his own organization to do that for him, and unlike the faceless men, he had many men.
Anyway, Edward did not wait any longer and launched a pincer attack on Riverlands from the Vale and Westerlands at the same time. Of course, Tywin Lannister did not want to see one of his final two allies die and tried to assist him.
Tywin only had Walder Frey and Roose Bolton at the moment, and if he lost Riverlands, he would lose both since there was no way for Roose Bolton to help him if Riverlands were in Edward's hands.
But in Edward's eyes, Tywin was an idiot in doing that. Tywin had asked for reinforcement from House Frey and House Bolton, but they did not even care about sending a reply back to Tywin. Walder Frey was not an idiot, and he would never help Tywin facing Edward, who could kill him and all his house.
Walder Frey had witnessed with his own eyes the massacre that Edward did to the Taragaryen's army during the rebellion when he arrived late. He would never follow them and decided to ignore Tywin's letter completely. He did not even bother sending a reply back.
As for Roose Bolton, he had some connection with Edward, and he preferred to delay angering the man, or everything he did would turn on him. Plus, he was not an idiot as House Stark was.
Bolton knew that the south was not safe, and he would never follow Ned Stark's footsteps. So he only sent a reply throwing the blame on the ignorant Walder Frey.
Tywin was probably doing that because he did not want to get surrounded in King's Landing, but what could his small army do in the end. Tywin sent a ten thousand men army to fight beside what remained of House Frey.
What made Edward more confused was that Tywin sent his only remaining son, Jaimie Lannister, who lost his two hands and could not even fight at the head of the army. Jaimie had only survived his death by luck after Tywin's agreement with House Bolton and House Frey.
Plus, After Walder Frey's death, all his men ran away or surrendered, leaving only two thousand men to defend against Edward's armies.
In the end, not only did Tywin achieve anything, but he also lost more soldiers that he could use to defend King's Landing. Jaimie Lannister got fleyed after he got captured in this battle.
Edward started to have some pity for Jaimie since it seemed that luck had run out for him in this timeline. He was the most unfortunate man in this timeline. Even Rhaegar and Jon Connington did not go through all this, even with Edward's hate for the two.
But not only did Jaimie Lannister get humiliated on Edward's hands in King's Landing after the rebellion, but he lost a hand to the same man in Winterfell. After that, he got captured by Rob Stark and lost another hand and a dick. And now, he got fleyed before his death.
Because Edward did not know how Tywin could make this foolish decision that could send his son to his death, he had to ask his men to get him fresh news about Tywin, and when this news came, Edward's expression changed.
It seemed that Cersei had finally done it. She poisoned her father with something that could make him restless. Tywin was no longer himself, the powerful and collected Tywin that Edward knew. Due to the poison, Tywin was distracted, and his thinking was cloudy for him to make the correct decision.
The one who was controlling everything behind the scene was Cersei, and she was foolish enough to make this wrong move. It seemed that after Jaimie returned to Cersei and she saw what happened to him, she blamed her father for what happened to him.
Plus, Tywin changed a lot after seeing what happened to his only remaining son and was more cruel and indifferent to Cersei, making her hate the man more and more. In the end, she decided to get rid of him. As for her brother and lover, after waiting for him patiently for a year, it seemed that she could not bring herself to love him anymore, and she decided to get rid of him in the fight against Edward.
Cersei wanted to use her trump card that she prepared for years and had spent much effort on, but Cersei still held some hope. She still had her youngest son, but she swore that she would make Edward feel her pains.
But the defeat had more foreseen changes. Not only did the people in King's Landing became more restless, but the leaders in the armies were also dissatisfied with what happened. Plus, the High Sparrow started making his appearance in the city, taking a part of Tommen's power. Cersei even made use of him to stabilize the city, which was already boiling with anger. She did not realize that it would be her end soon.
After Edward read what happened to Tywin, his heart hurt a little since the one that entertained him in the whole realm turned into a puppet in his daughter's hands. Edward did not know what would make him enjoy the game any longer since Cersei did not reach her final bitch stage.
Edward was disappointed that he decided to return to Storm's Eye after taking down Riverlands. Edward decided to send his son, Lyonel, to take the North himself. Since the brat would marry Sansa, he had to prove himself to her by returning her homeland to her hands. But Edward did not forget to send Sansa, Arya, Wilyam with him. His only order was to take that bastard Ramsy Bolton back to him alive.
You all could not imagine how Edward felt at the moment. It seemed as if his childhood friend that he grew up with had died all of a sudden, and he got left in the world alone. Although Edward hated the Lannister because Tywin almost killed him more than one time, Tywin was his opponent in the long run.