sinister Slothrop

[Terrance]

Thomas Pynchon's "Gravity's Rainbow" (1973), which depicted a
nightmarish world in love with death and torn between acute paranoia and
fears of random chaos. [...]

I didn't read the article or essay, but this sounds OK to me. 

And  sinister? 

Again, I didn't read it, no time, but "Sinister"  could be just the
adjective for Slothrop, depending on how the author used the word. 

Sinister:  Presaging trouble; ominous: sinister storm clouds.  Attended
by or causing disaster or inauspicious circumstances. Sinister usually
implies impending or lurking danger that makes its presence felt by
ominous signs or portents. 

Thanks for the notes and comments Michel and all.