“The Abandoned” is episode six of season three of Star Trek: Deep Space Nine.
Quark buys some bits of a wrecked ship found in the Gamma Quadrant from a freighter captain he knows. One of the pieces of wreckage turns out to be a pod with a baby inside it, which results in Quark turning everything over to the station.
The baby is rather unusual. For one thing, within a short period of time after his release from the pod, he becomes a teenager. Dcotor Bashir discovers that the child has been heavily genetically engineered (something not exactly popular in the Federation), and is maturing at an incredible rate. It rapidly becomes apparent that the boy is an infant Jem’Hadar, the elite troops of the Dominion. Only Odo, being a Founder, is able to have an influence on the boy, because obedience to the Founders is engineered into the Jem’Hadar.
The Federation wants to take the boy away for examination and study, as this is an opportunity to learn more about their enemy. Odo takes charge of the boy, because he wants the latter to have a chance to grow up normally. It seems that the genetic engineering is very strong, including a drug addiction, and Odo’s attempts do not go well.