(Interestingly enough, both the alien tech and the practice of personality wipes will pop up in later episodes, as will a parallel between June Lockhart’s career and Dr. Franklin. Also, June Lockhart is freaking scary when she gets angry.)
There’s a lot of Angry Garibaldi in that C-plot, bu the way as well as a lot of Tormented Talia. Neither does the sort of job that will show up on anyone’s resume, though the serial killer is suitably creepy. That said, the whole issue of criminal punishment, capital punishment, and mind-wiping provides some interesting futurism-fodder.
The “B” side has Londo taking Lennier under his wing to show him the seamy underside of B5 — mostly for Londo’s benefit. Things eventually go pear-shaped during a poker game, where an hitherto-unsuspected aspect of Centauri physiology is revealed, to a most amusing conclusion.
Overall, despite the Chekhovian guns put up on the the mantle, there’s not a huge amount of arcishness to this Joe Straczynski episode, but it’s still entertaining, and a cut above a lot of earlier eps in the season.
(Though they never share any scenes together, it’s also amusing seeing both June Lockhart and Bill Mumy in the same show again, three decades after “Lost in Space.”)
Most Dramatic Moment: June Lockhart, sweet and kind and saintly, reveals what happens when you threaten her, her daughter, and her friends.
Most Amusing Moment: Lennier decides to take a vow of silence over what he’s just learned about Centauri physiology.
Most Arc-ish Moment: Dr. Franklin gets a description of June Lockhart’s career and the mistakes she made along the way. Foreshadowing, much, Joe?
Overall Rating: 3.5 / 5 – Solidly good, if relatively inconsequential, and hampered by some less-than-stellar acting. I take back an earlier note — this is the last episode that Londo can be the happy-go-lucky sybarite he plays so often in Season 1. Things start to go south for him right … about … now.
Lurker’s Guide: http://www.midwinter.com/lurk/countries/us/guide/021.html
Babylon Project: http://babylon5.wikia.com/wiki/The_Quality_of_Mercy
IMDB: http://www.imdb.com/title/tt0517712/
AV Club: http://www.avclub.com/review/babylon-5-babylon-squaredthe-quality-of-mercy-83593
Noise2Signal: http://noise2sig.nl/2011/04/15/babylon-5-the-quality-of-mercy/

We also learn that despite his aw-shucks demeanor, Lennier is not to be trifled with…
+George Wiman Hell, yeah!
I love Babylon 5!!!! Such an underrated show!