4. Condoning the brutalizing of peasants
During the War of the Five Kings, Tyrion works alongside his father while he conducts a brutal war that involves murdering peasants and burning their fields. The Riverlands get plundered by the Mountain and Amory Lorch while Tyrion stands idly by. Through Arya’s chapters, we see scores of peasants get tortured and put into labor camps at the direction of the Lannister army. While serving as Hand of the King while Tywin is away at war in A Clash of Kings, Tyrion is confronted with these atrocities and simply says that this is how war is waged.
3. Blowing up the Blackwater
While one can argue that Tyrion saved the capital of King’s Landing with this move, there is no denying that his plan got a lot of people killed. Just before Stannis Baratheon invades the city with a massive army from the Reach and Stormlands, Tyrion’s man Bronn uses a massive chain to trap many of Stannis’ ships in Blackwater Bay. Tyrion then orders that casks of wildfire be lit and launched at the ships, effectively lighting the bay on fire. Thousands of men are cooked alive by the scorching flames.
From the perspective of Davos Seaworth, this is the worst thing imaginable; three of his sons die on the Blackwater. Even though Stannis was probably not willing to negotiate, Tyrion was Hand of the King during this time and he was more concerned with burning his enemies alive than finding a diplomatic solution to the conflict. He had already rejected the peace terms with the North and Riverlands which could have returned Sansa to her family and Jaime to his. Tyrion had many chances to be the bigger man but he routinely acted like his father Tywin would instead.