Cheng Xin

Cheng Xin was an aerospace engineer, Swordholder, and diplomat.

Early Life
Cheng attended the same college as Yun Tianming. Cheng and Yun had a few brief connections during their time in school, but did not have a strong relationship.

Crisis Era
Cheng Xin began working as the Aide to the Directory of the Technology Planning Center for the PDC Strategic Intelligence Agency (PIA) shortly after completing her graduate studies around the beginning of the Crisis Era. She proposed the idea for the PIA's Staircase Program, a project to launch a spy probe at the Trisolaran Fleet. Cheng reconnected with Yun Tianming when Yun was selected as a candidate for the Staircase Program. Coincidentally, Yun purchased the rights to the star DX3906 as a gift for Cheng using money gifted to him by a college classmate. Shortly after the launch of the Staircase program, Cheng entered hibernation.

Deterrence Era
Cheng Xin was awakened from hibernation 264 years later in Year 61, Deterrence Era by the UN and Solar Fleet, who wished to take control of DX3906. After awakening, Cheng met 艾 AA, an astronomer who had discovered the planets that surrounded DX3906. Later in Year 61, Cheng Xin was chosen as one of the candidates for the next Swordholder. Later that year, Cheng was shot by Thomas Wade, one of the other Swordholder candidates, in an assassination attempt. Cheng survived the attack and Wade was imprisoned.

In Year 62, D.E., at the age of 29, Cheng Xin was selected by the PDC to succeed Luo Ji as the next Swordholder. Cheng officially became the Sworldholder during a handover ceremony at the Deterrence Center on November 27, Year 62 D.E. and held the title for approximately 10 minutes until 4:27:58 PM on the same day when the Trisolarans destroyed the Gravitational Wave Universal Broadcast System, ending the Deterrence Era and marking the beginning of the Post-Deterrence Era.

Post-Deterrence Era
Cheng Xin and AA moved to Australia in the first wave of forced migration during the Great Resettlement. They both lived with an old man named Fraisse near Warburton. Cheng met the imprisoned Wade, who urged Cheng to escape Australia before the Great Resettlement was complete.