A fairly standard "filler" episode for the most part, though not without interest for being the first of several episodes to use Dr. Franklin and Marcus as an unlikely team.
Corwin is celebrating his promotion to full lieutenant - a promotion which, while well-deserved, poses a problem for Sheridan and Ivanova. Sooner or later, with his new rank in C & C, Corwin is bound to find himself in the middle of Sheridan's conspiracy. They need to know whether Corwin will be loyal to them, or whether he will report them to Earth Central. Ivanova agrees to invite Corwin to her quarters for a private chat to feel him out.
Meanwhile, Dr. Franklin finds an interesting anomaly in the autopsy of a lurker from Down Below. The man, who was a drug abuser, has a parasite attached to his spinal column. When Ranger Marcus Cole finds several of his contacts in Down Below acting strangely, he enlists Franklin's aid to investigate - leading them to discover that these snake-like parasites are being deliberately implanted in several lurkers. Is it an Invasion of the Body Snatchers? Or is something else going on beneath the surface?
Though a fairly minor episode, this installment is enjoyable on its own terms for a number of reasons. Chief among these is the unlikely combination of Marcus and Dr. Franklin.
Marcus remains outwardly a goofball (though his "goofiness" is toned down a bit here from Voices of Authority). He jokes with, nags, and needles those around him until they either agree to assist him (Dr. Franklin) or get hopelessly irritated by him and flee (Garibaldi). Beneath that exterior, however, Marcus actually has a lot in common with Garibaldi - most specifically in that when Marcus decides something is troubling him, he won't let go of it until he has the answer.
Stephen also shares this trait, albeit in a different way. While Marcus, even through his concern for his friends and contacts, takes a kind of joy in having a puzzle to pursue, Stephen doesn't enjoy the puzzles. One senses that Marcus gets pleasure from throwing himself into impossible situations and trusting to fortune that he'll be able to think, fight, or talk his way out again. Stephen would as soon not have to deal with life-and-death situations; he sees far too much death in Medlab to find it fun or adventurous to face it outside of his job. One could almost parallel them with Don Quixote and Sancho Panza. Marcus is Quixote, pitching himself headlong into situations without pausing to think first; Franklin is Sancho, fond of the more headstrong man, but also trying to exert some influence to hold him back from his worst excesses (and, like Sancho, getting himself into trouble in the process).
It is nice to see Corwin getting more screen time, and the scenes centered around his "date" with Ivanova are quite amusing. Joshua Cox's Corwin is a mass of social confusion. The look of horror on his face as he mulls the possibility that Ivanova may have just asked him out is hilarious, as is his stammering uncertainty about the situation as he goes to a shop to buy flowers... only to deny that he actually bought them when he arrives at Susan's apartment, then look on in horror (once again) as it becomes apparent that she quite likes the gift that he denied having purchased.
The conversation Ivanova and Corwin have in her apartment is as interesting as their other interactions are amusing. As Ivanova notes early in the episode, "this is the part of all this I really hate." She has to subtly interrogate Corwin, trying to determine where his true loyalties lie. Corwin, in the meantime, is in the presence of a superior officer, having just been given a major promotion; when the questions begin, he wouldn't be entirely ridiculous to think that he was being tested. So Corwin struggles for the right answers to Ivanova's questions, and ends up giving all the wrong ones... which also nicely parallels his flower debacle.
There's not much that's actively bad about this episode, though as the sparse review above might indicate, there's little that's fantastically good here either. This is a minor standalone, and a fairly generic one at that. For the most part, this feels like "filler." There's nothing wrong with filler, in and of itself. But I do wonder why J. Michael Straczynski insisted he had to write all 22 episodes of the season, if one of those episodes was going to be this one. Certainly, I can think of episodes by other writers from the first two seasons that far surpass Exogenesis, both in terms of overall entertainment and in terms of advancing the characters.
For the most part, this episode just feels like a placeholder. It's OK to watch, but there's not much here to get worked up over. Indeed, this was the one episode of Season 3 I had no memories of whatever when I hit the "play" button. And save for some of the dialogue between Franklin and Marcus in the cell, I can't say there's much that really came back to me while watching it. Exogenesis had effectively dropped out of my mind from the first viewing. And I won't be surprised if it drops out of my mind again after the second viewing.
Not bad, as filler goes. But it does feel largely like "just filler."