Cao Shuang

And under this Wei emperor, Cao Rui, the fortunes of the Sima family and the influence they had in the kingdom of Wei continued to grow.

After Cao Rui's passing in 239, we had a Wei general, Cao Shuang, ruling as regent for the seven-year-old kid emperor, Cao Fang.

As the surname indicates, he was one of the Caos.

Cao Shuang actually served as co-regent along with Sima Yi, and as far as both of them privately felt, two regents were one too many.

In order to neutralize Sima Yi as an ongoing potential political threat, Cao Shuang maneuvered to force Sima Yi to retire from the government.

And it was Cao Shuang's belief that, having Sima Yi out of the halls of power, he'd be too old and unwell to pose a threat.

Sima Yi knew what this was all about and went along with it, deliberately feigning poor health and frailty in front of Cao Shuang.

He must have done a good job because after a while, the Caos took their eyes off of him.