Who is Tinker from Sarah Kane: Complete Plays and what is their importance?

Tinker is a drug dealer and doctor, and he is the commander of the university and concentration camp in "Cleansed". Tinker is a psychopath who dedicates himself to the cruel undermining of relational bonds. At the beginning of the play, he kills the addict Graham with an overdose of heroin. When Graham's twin sister Grace enters the play, Tinker sedates her and keeps her in the institution. Tinker tortures the inmate Carl into betraying his lover Rod. Then, he proceeds to cut off Carl's tongue, hands, and feet to prevent him from communicating with Rod. Tinker also prevents the depressed boy Robin from taking comfort from Grace, driving him to suicide. Tinker regularly visits an exotic dancer, begging for her friendship and pretending she is Grace. In the latter scenes of the play, Tinker gives Grace electroshock therapy and performs a haphazard sex change on her. Realizing this is not what she wants, Tinker returns to the exotic dancer and makes love to her.