Sima Yi was the strategist of
Wei. He was born in179-251 A.D. Zhongda (his style name) lived to be an
old age of 72, which was then thought to be a long time. His father was Sima Fang, and his
children were Sima Shi and Sima Zhao. His grandsons were Sima Yan and Sima
You.
Personality wise, Sima Yi was a wicked,
conniving strategist, merciless with dark intent and little regard to those
he might injure in the name of strategy. In the game, he loves fire attacks and ambushes.
All who compared to his intelligence, he disliked. Sima Yi resented
Shu's strategist, Zhuge Liang very much. It always seemed that Liang was one
step ahead of him. Sima Yan, his grandson ended the
kingdom of Shu. Eventually, Sima Yan and Sima Zhao ended the Han,
beginning the Jin dynasty.
-Donated by Kylie
Note from Jubi...
Sima Yi is often (in the game portrayal) seeking to use someone for his own personal benefit; in a cutscene of Dynasty Warriors 5, he is seen persuading Wei Yan to defect, and in Pang De's ending again tries to convince Pang De to assist him with his prowess in battle.
Bonus Note:
In Warriors Orochi, he is more or less forced to fight alongside Zhuge Liang temporarily, since he sides with Orochi as does Liang (who eventually defects after capturing and forcing Da Ji to reveal Liu Bei's location).