Roger Harding is stuck. Unqualified to work anywhere but the library at his old university and only still there due to an error in HR. He is unable to cope with normal life due to his rigidity and lack of social skills, and the only solace in his life is his companionship with Elly Watson, an old friend of his who lives in the apartment above his.
Until one day, Elly is murdered, and Roger awakens to find blood gushing from his ear. As he attempts to come to terms with her death, his world is torn apart by nightmarish hallucinations and strange changes wracking his own body. An otherworldly parasite, let into reality by the ritual that killed Elly, has taken up residence in Roger's own flesh.
As he deals with this, her killer continues to taunt Roger by leaving the murder weapon for him to find and by appearing before him. Gradually, it becomes clear that he already is the sort of monster that Roger fears becoming: a deathless, unkillable chimera with no free will of his own.
Well done! The imagery as you progress further into the story take on a more grotesque, visceral feel, adding to the general eeriness. It is also a pleasure to read the works of a good friend. I would recommend this!