Kessler has a fetish for female paraplegics and an inability to have an erection unassisted : he claims this is the result of the numerous times Butcher has kneed him in the groin when information is needed .
Kessler has a fetish for female paraplegics , due to his inability to have an erection unassisted . 
 This may have been a result of the numerous times Butcher has kneed him in the groin when information is needed .