Andrei Vezenskiy (Russian: Aндpeй Вeэeнcкий) was an ordinary Russian soldier who volunteered, along with tens of thousands of others, for a project to try and stop the Crawler infections that would lead to the extinction of the Chimera.
When Vezenskiy was given the injection by a Dr. Fyodor Malikov, the process went satisfactory and becoming immune to the Chimeran virus. But on the November 7th, 1927 the men began to change, as they undergo extreme dementia and suffering traumatic nightmares as a result of the injection that transformed them into the Cloven. Vezenskiy apparently became the 'unofficial' Cloven leader. Malikov interviewed him but Vezenskiy started to attack him.
On April 20th, 1928, Malikov fled, though Malikov's chief assistant Grigori Yefimovich Novy wanted the Cloven to retreat to Moscow but Vezenskiy refused, claiming that the Cloven are not like the Leben Geist but in fact the Lyutaya ("the Devils"). On August 12th, 1930, Vezenskiy fled to the west and gradually succumbing to his insanity.