Episode: ENT: Similtude

An engineering experiment gone awry leaves Trip with incurable brain damage. Phlox proposes and unorthodox treatment: growing a fast growing symbiont to provide needed neural tissue. Ethics are brought into question when it's discovered that, contrary to Phlox's original assessment, the symbiont would have to die to save Trip's life. The resolution of this story left me with a bad taste in my mouth (spoilers follow). It's as if you had a kid with two bad kidneys, decided to have another kid and donate his kidney, and when he is born with only one good kidney say "Sorry kid. The only reason we had you was to give Big Sib your kidney. Yoink!"