Plot summary
A ship carrying Vedek Bareil and the Bajoran spiritual leader Kai Winn (Louise Fletcher) to Deep Space Nine for peace negotiations with the Cardassians suffers a mishap, and Bareil is left gravely injured. Dr. Bashir (Alexander Siddig) finds that Bareil is braindead and tries to console Kira.
During the autopsy, Bashir discovers that Bareil's nervous system still shows signs of activity. He manages to revive Bareil by regenerating his brain. Kai Winn is pleased and wants Bareil to continue managing the negotiations, given his greater experience and diplomatic skill.
Bashir soon discovers that the revival is damaging Bareil's internal organs. He advises Bareil to go into stasis so that Bashir can find a solution, but Bareil refuses; he insists that he must finish the negotiations and create peace for his people. Bashir considers giving Bareil the experimental drug Vasokin, which would increase the blood flow to his organs and allow him to resume negotiations, but would ultimately damage his internal organs further.
The talks resume, but Bareil's condition continues to deteriorate, especially with Kai Winn continuing to probe him for advice when he should be recovering. Eventually, the Vasokin treatments begin to inflict brain damage, and Bareil falls unconscious again. Winn insists on keeping Bareil alive at all costs; Bashir accuses her of only wanting him alive so he can be a scapegoat in case the negotiations fail.
Bashir replaces the damaged part of Bareil's brain with a positronic matrix. The surgery is a success, but Bareil is still severely brain-damaged with a life expectancy of only a few months, just enough time to possibly conclude his negotiations with the Cardassians. Kira speaks with him, but he barely recognises her and is no longer the man she fell in love with.
Bareil is kept alive long enough to aid in completing the negotiations, and the treaty is signed between Bajor and Cardassia. As Bareil's condition worsens, Kira asks Bashir to replace the remainder of his damaged brain with positronic matrices, but Bashir refuses on the grounds that it will remove any 'spark of life' that Bareil has left. Winn agrees that it is time to allow Bareil to die. The episode closes with Kira at Bareil's bedside, recounting for a slowly dying Bareil how she first fell in love with him.
In a side plot, Jake Sisko (Cirroc Lofton) must confront his Ferengi friend Nog (Aron Eisenberg)'s misogynist attitudes toward women and dating.
Credits
Adapted from Wikipedia contributors, Life Support (Star Trek: Deep Space Nine). Paragraphs and formatting adjusted; illustrations, reference markers, block quotations and non-story material omitted.