Generally Season 5 to me is one of the stronger seasons of 'Criminal Minds', though there are a few lesser episodes. "Parasite" is one such episode and also one of the show's overall weaker episodes.
"Parasite" is not a bad episode, there are worse 'Criminal Minds' episodes definitely and a fair few wasted potential episodes, Season 9's "200" and to a lesser extent Season 11's "Derek" being notable examples. At least "Parasite" actually feels like 'Criminal Minds', and doesn't waste the team and make them dumbed down or out of character, and at least it doesn't have as many unresolved questions or insults the intelligence.
At the same time though, it doesn't ever really rise above okay, rather an average episode and for 'Criminal Minds' it's pretty bland. There are good things certainly, even when this reviewer doesn't care or intensely dislikes something she still looks out for the good. 'Criminal Minds' has always been well made, and while this reviewer prefers the darker and grittier production values "Parasite" is still made with plenty of class and style. The music as ever is suitably haunting and hypnotic. The script is tight and has the right balance of lightness and grit with very little unnecessary fluff, apart from the overly close banter between Morgan and Penelope that can on the show in general border on cheesy, over-used and annoying.
Still love the chemistry between the team, the thought-provoking book-end quotations, what was done with Prentiss here and the entertaining and intriguing procedural and crime-solving aspects. The acting is mostly good, with the leads on top form. There are exceptions, Victor Webster fails to bring menace or distinction to the unsub Bill Hodges, who is one of the show's blandest and most forgettable in general, and Bryce Robinson's acting as JD is barely existent, one of the weakest child performances on the show without a doubt.
What stops "Parasite" from being any better is that much of the story is not always very interesting apart from moments of spark with the team, the atmosphere is bland, pacing can be dull and the storytelling is pretty formulaic fare with not much tension. Not much stands out, including as said one of the show's most forgettable unsubs, and it doesn't really come to life apart from when the unsub becomes more deranged at the end and agreed about the refreshing darkly humorous touch (though it may be ridiculous for others). All the supporting characters are dull.
All in all, an okay episode but rather bland and never rises above formulaic story-wise and average as an episode of 'Criminal Minds'. 5/10 Bethany Cox