Who is this Cheng Pu character they are adding to DW9? I've seen him as an NPC I think but I don't know much about him.
He was one of Wu’s most important generals. Among Wu’s officers, his position is comparable to that of Cao Ren and Guan Yu.
Cheng Pu joined Sun Jian prior to the Yellow Turban Rebellion and fought in all of his battles, serving as Sun Jian’s right-hand man. Cheng Pu continued his service under Sun Ce. Of all Sun Ce’s commanders, no one had more accomplishments than Cheng Pu. He provided remarkable service in a huge number of battles: Wan, Deng, Yangren, Huan, Hengjiang, Dangli, Moling, Hushu, Jurong, Qu’a, Wucheng, Shimu, Bomen, Lingzhuan, Yuhang, Xuncheng, Jing, Anwu, Lingyang, Chun’gu, Xunyang, and Shaxian. In all of these battles, Cheng Pu earned the most valor. At one point, he even personally saved Sun Ce’s life. Sun Ce pressed too deeply into an enemy formation and was surrounded, so Cheng Pu personally fought his way through to bring Sun Ce out.
After Sun Ce’s death, Cheng Pu ensured that the army would follow Sun Quan without objections. Sun Quan relied on him heavily and gave Cheng Pu command over the army, along with Zhou Yu. The two held joint command at Wulin/Chibi and at Jiangling.
In addition to being an incredible warrior, Cheng Pu was also a very intelligent man who was well-versed in stratagems. He was also noted for his good looks, as well as his many battle-scars.
Basically, in every battle the Sun family fought up until about 211, Cheng Pu was right there with them. And he was the big hero of almost every single one. He was the strong right hand of the Sun family, the steady rock that provided stability to their army.