'''Season 1, Episode 21:'''
!The Quality of Mercy
[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/b5thequalityofmercy_4846.jpg]]
[[caption-width-right:350:That device right there is going to be [[ChekhovsGun really important in the future]].]]
->''"It works, all right. It restores, renews, invigorates. It is good for ailments of the flesh, the blood and the bone."''
-->-- ''' Dr. Laura Rosen'''

-----

Londo is on a call with a Centauri official about diplomatic relations, specifically maintaining good relations with possible allies. Londo protests that he's doing what he can and signs off. He mutters as he gets up and heads out, encountering Lennier as he does so. Sensing an opportunity to maintain good relations, he asks the Minbari about himself. Lennier's answer is very brief. "From birth I was raised in the ways of the Religious Caste. Six months ago, I came here. There is nothing else." Londo presses him and eventually offers to take him to get to know the Babylon 5 that he knows.

Elsewhere, one Karl Edward Mueller has just been found guilty of murdering two lurkers and one [[CopKiller security officer]], with sentencing to he handed down the next day. Elsewhere still, Ivanova goes down to Downbelow to confront Dr. Franklin about an unauthorized clinic he's been running. He doesn't want to shut down because there's a dozen people outside waiting to see him. Ivanova tells him there's only half a dozen, but she agrees to not tell anyone about this if she can help out. Franklin sends her in back to get changed into something more practical, then goes to see where the other half dozen went.

In a meeting to decide Mueller's fate, Garibaldi is loudly advocating spacing him. The ombudsman disagrees, saying that's only an option for treason. Legally the only recourses they have are life imprisonment, which they don't have the room for and Earth Central isn't willing to cover, or a mind wipe, which will require Talia's services to scan Mueller before and after and confirm a successful wipe. She is reluctant, not wanting to go inside a SerialKiller's mind, [[Recap/BabylonFiveS01E09Deathwalker having done it once before]], but she eventually agrees.

Franklin arrives at a flat in Downbelow where a woman named Laura Rosen is running another medical practice. He finds her hooked up to a strange machine along with one of her patients. When she's done she addresses Franklin, saying she'd been expecting him to come pay her a visit. He examines her device, which she claims can cure anything from the cold to Stafford's disease. He claims it's a hoax and calls her a quack. Just then another woman comes in and starts yelling at him for talking to her mother that way. She makes him leave, but he says he'll be back.

The ombudsman sentences Mueller to death of personality, meaning he will be scanned by a telepath then mindwiped and programmed with a new personality to spend the rest of his life serving the community he harmed. Later in Medlab, Franklin is tasked with preparing the equipment necessary, and takes the opportunity to ask Garibaldi to look into Rosen's practice.

At the Dark Star, Londo has just arrived with Lennier in tow. The Minbari is quite obviously out of place there, but Londo leads him up to the front near the stage, but when he goes for his credit chit, he claims he left it in his quarters. Lennier's protest over using his chit is cut off when the dancer onstage [[DressHitsFloor drops her skirt]] and Lennier finds himself entranced. A waitress brings two drinks, and Lennier asks if there is any alcohol in them. Londo brushes his concerns aside... until Lennier explains what happens if a Minbari drinks it, at which point Londo hastily grabs his glass and orders a water for him instead.

Franklin finds Rosen's daughter, Janice, and tries to talk to her about the device. She tells him how she used to be a physician, until she started abusing stims to work longer and eventually lost her license because of it. Franklin tries to explain that her mother is just keeping people from getting the treatment they need. She gets angry and tells him not to take this away from her mother, threatening to fight him if he does.

Londo has finally gotten Lennier to open up about his past, and is being bored to death with Lennier recounting his years of study in linguistics. When he tells how he started studying mathematics next, specifically probability, Londo perks up and decided to introduce Lennier to one of the greatest means of communication, what the Earthers call "Poker."

Talia prepares herself for her encounter with Mueller. He is not cooperative, but there's nothing he can do. She begins the scan, and immediately sees his memory of killing the security officer. "Another voice for the choir," he says, and shows her the faces of all the people he's killed over the years. Talia lurches out of his mind and backs away from him with a horrified look, as he says ominously, "I'll save a place for you."

Franklin is looking at some follow-up reports on the people Rosen's treated, and is stunned to see that they actually are improving. He heads off to see her, and watches as she treats another patient, running a scan as he does. When she's finished he offers an apology, then tells her what he found: the machine is taking her life energy and transferring it to her patients. She also reveals that she has an incurable case of Lake's Syndrome, which gives her about three years to live. Eventually the two come to an agreement. She will continue to use the machine, as long as she comes to Medlab each week for a checkup. She also asks that he not tell her daughter what he knows. She wouldn't understand.

Garibaldi finds Talia in the garden. She compares her experience to some alien minds she's been in, saying no matter how different they were, they had more humanity than what she just saw.

In the casino, Lennier is doing quite well, as indicated by the pile of chips in front of him, and the other player's reactions whenever he blurts out the odds of his current hand. Londo starts lifting cards from the far side of the table by means of a tentacle like appendage that comes out of his shirt, until someone puts a pitcher of ice water right on top of it. Londo's attempts to get it out draw the attention of the other players, who realize Londo's been cheating. One of them tries to attack him, but Lennier knocks the aggressor down. He then tries to get Londo and leave, but the other patrons are now forming a menacing circle around the pair.

The time has come for Mueller and he is led off, but in the lift he makes a break for it. Garibaldi manages to shoot him, but Mueller gets away. When he's informed of what happened, Franklin figures Mueller will likely seek medical attention and calls his assistant to be on the lookout. She mentions that hardly anyone's been by, they've all been going to Rosen. Franklin realizes that's where he's gone and races there. He finds Mueller holding Janice at gunpoint and Rosen on the machine, looking tired, apparently having already been strapped in for a while. Mueller keeps Franklin at bay with the gun, and his actions cause Rosen to conclude that he will kill them anyway as soon as she's done treating him. She reverses the machine, putting her Lake's syndrome into him, curing her but the process proves fatal to him.

In the courtroom, Rosen is found to have [[KillingInSelfDefense acted in self defense]] and is allowed to go, on the condition that the device is turned over to station personnel. She feels differently, saying she did the necessary thing, which is not always the right thing.

With the Mueller situation over, Garibaldi can now concentrate on other things, like who started the fight in the casino. Ivanova informs him that they've already identified the responsible parties. She tells him, provoking a pronounced reaction. "[[BigWhat WHAT?]]"

Sinclair is facing the two of them, asking for an explanation. Lennier takes responsibility for the whole thing, saying he asked Londo to show him around, and unwittingly caused offense which lead to the fight. Sinclair informs them diplomatic immunity means they can't be prosecuted, but he does insist they pay for the damages. After he leaves, Lennier asks Londo just what those tentacles were. Lennier is deeply embarrassed and takes a vow never to speak of it.

Rosen delivers the device, and says she is leaving, going off to try and find a way to redeem herself for what she's done.

!This episode contains examples of:

* AccidentalInnuendo: In-universe: when Ivanova comes to check out Dr. Franklin's unauthorized clinic, he mistakes her for his next patient. "You can start by [[TakeOffYourClothes taking off your clothes]]." To which she responds, "Not without dinner and flowers."
* BackAlleyDoctor: Laura Rosen and her device.
* BattleButler: Lennier is quite a capable fighter, doing flying kicks and what not. It's implied that Minbari like him who study in temple are all like this, making them a ProudScholarRace. BewareTheNiceOnes indeed.
* BeginnersLuck: Lennier keeps winning at Poker despite not even trying. His opponents, especially Londo, are annoyed by this.
* BizarreAlienBiology:
** Centauri are shown to have a series of tentacles growing out of their flanks. These are the males' reproductive organs. And they are prehensile...
** Minbari [[CantHoldHisLiquor do not react well to alcohol]], ''at all'', as Lennier reveals to Londo just as he's about to take a sip of a drink that Londo (thinking he was just being a stick in the mud) had assured him contained no alcohol.
--->'''Lennier:''' Even a small quantity can cause violent, homicidal rages.\\
'''Londo:''' ''[grabs Lennier's glass]'' Ah, alcohol! My mistake.
* CallBack:
** [[Recap/BabylonFiveS01E09Deathwalker As seen previously]], this isn't the first time Talia's had to scan the mind of a murderer.
** [[Recap/BabylonFiveS01E15Grail Ombuds Wellington]] is back.
* CastFromHitPoints: The device transfers life energy from one person to another. Dr. Rosen uses her ''own'' life energy to heal others, but the device was originally intended as a form of capital punishment, draining the life of a criminal to give others healing. This is in fact what Dr. Rosen does to Mueller at the end.
* ChekhovsGun:
** The healing device will be used at least once more to help people in dire situations.
** Lennier's statement that Minbari will lie to save the honor of someone else becomes a major plot point when Captain Sheridan [[Recap/BabylonFiveS02E14ThereAllTheHonorLies has to defend himself after killing a Minbari who attacked him]].
* CopKiller: Mueller shot a security officer along with two lurkers. Garibaldi wants to space him for it.
* DeadlyDoctor: Laura uses the device to kill Mueller to save her daughter. She is then distressed over having taken a life, no matter how defensible.
* DeathOfPersonality: The {{Trope Namer|s}}. Mueller is sentenced to have his personality and memories erased and replaced with FakeMemories and a persona that will want to serve society in a menial role, as the standard punishment for murderers, believed to be more humane than execution. A machine is used to perform the procedure and a telepath is present to scan the condemned before and after to confirm the thought patterns have changed. Mueller escapes before the sentence can actually be carried out. [[spoiler:It's not until [[Recap/BabylonFiveS03E04PassingThroughGethsemane Season 3]] that we see someone who has been through it]].[[invoked]]
* DistractedByTheSexy: Lennier finds the dancers in the Dark Star night club... fascinating.
* FictionalDisability: Laura Rosen is revealed to be dying from Lake's Syndrome. The only distinguishing characteristic is that it induces almost unbearable pain, described by Rosen as akin to having arthritis, blurry vision, the intestines seeming like they are on fire, and veins burning with pain. When Mueller got a dose of it via the alien device, he was instantly incapacitated by the sheer intensity of it.
* {{Foreshadowing}}: Listen closely to Janice's description of how Dr. Rosen lost her medical license.
* HelpingAnotherSaveFace: Helping another save face is one of the few situations where Minbari culture allows one to lie. Seen most obviously in "[[Recap/BabylonFiveS01E21TheQualityOfMercy The Quality of Mercy]]", when Centauri Ambassador Londo Mollari is caught cheating at cards with his [[BizarreAlienBiology prehensile genitals]] leading to a bar brawl, a Minbari, Lennier is willing to take the blame for the fight.
* HighTurnoverRate: The reason there's a shortage of telepaths who specialize in scanning the minds of murderers; looking inside such a mind is ''very'' stressful on them.
* IDidWhatIHadToDo: How Rosen feels about draining Mueller's life when he threatened herself, her daughter, and Dr. Franklin. Doing what is ''right'' versus doing what is ''necessary'' would become one of the show's recurring themes.
* KillingInSelfDefense: Rosen is not prosecuted for killing Mueller because of this, though she does have to give up the device.
* LetUsNeverSpeakOfThisAgain: Lennier takes a vow of silence over what Londo tells him about Centauri physiology... and thus what exactly Londo was using to cheat at cards with.
* LiteralistSnarking: Sinclair and Londo go back and forth with this:
-->'''Sinclair:''' I'm still waiting for an explanation, gentlemen.\\
'''Londo:''' Yes, and I'm prepared to give you one, Commander, as soon as the room stops spinning.\\
'''Sinclair:''' This station creates gravity by rotation. It never stops spinning.\\
'''Londo:''' Well, you begin to see my problem.
* LiteraryAllusionTitle: ''Theatre/TheMerchantOfVenice'' IV.i
* LostTechnology: The origin of the healing device is never made clear, but the markings look similar to Vorlon writing.
* MamaBear: Dr. Rosen uses the device to kill Mueller after he threatens her daughter's life.
* AMindIsATerribleThingToRead: As seen in "[[Recap/BabylonFiveS01E09Deathwalker Deathwalker]]", the mind of a SerialKiller is not a fun place to visit. Talia is horrified by what she finds in Mueller's mind, a dark space filled with a "choir" of all his past victims that he believes will sing him up to Heaven when he dies. By episode's end, we can be reasonably certain he's headed in the other direction.
* MushroomSamba: Not in the episode itself, but it was actually written in one, while JMS was suffering from a bad flu. He woke up one day to find the script on his table, with no memory of having written it.
* OhCrap: Londo has a mild one after buying Lennier a drink then hearing that alcohol causes literally violent reactions and hastily grabs the glass.
* [[ShoutOut/ToShakespeare Shout-Out: To Shakespeare]]: The title is taken from ''Theatre/TheMerchantOfVenice''.
* TakingTheHeat: Lennier takes the blame for the incident, despite it being mostly Londo's fault, to save Londo's reputation.
* TheseHandsHaveKilled: Dr. Rosen definitely takes "first do no harm" seriously, but was forced to use her miraculous alien healing device to kill a man who would have killed her, her daughter and Dr. Franklin. That this was ruled to be perfectly justified self-defense, or that the manner of killing means she's now free from her awful terminal illness, does nothing to alleviate the profound horror she feels at having taken a man's life.
* VerbThis: After giving Londo some instructions, a Centauri minister says, "I'll be in touch." After the line is closed, Londo replies, "Touch these." He then gestures to his sides, which are where the Centauri "attributes" are located. (It's not until later in the episode that the significance of this gesture becomes clear, though it could possibly be guessed.)
** For extra emphasis, note that the statue of Li, the hermaphrodite Centauri goddess of fertility, is visible through the whole scene.