“Chimera” is episode fourteen of season seven of Star Trek: Deep Space Nine.
O’Brien and Odo are returning to DS9 in a runabout after being away for a day at a conference. Odo has bought Kira a gift – two in fact – and Miles hasn’t brought Keiko anything. So he offers to buy the chocolates from Odo.
Then, a large space creature swims past them, before going behind. There is a thud on the runabout and the creature disappears. There is also something inside the runabout now, and it exists through a vent – it’s another Changeling. The new Changeling says that he sensed Odo, and had never encountered another metamorph before, only monomorphs. Odo says that the newcomer must be one of the hundred infant Changelings sent across the galaxy, as Odo was. O’Brien wants the new Changeling in custody – there’s a war going on with the species after all – and the newcomer agrees -but only if Odo vouches for his safety, as he doesn’t trust humanoids.
Odo later tells Sisko that Dr. Bashir has examined the new Changeling and has confirmed that he isn’t infected by the disease that has infected the entire Link (which Weyoun Six told Odo about in “Treachery, Faith and the Great River”) and that he therefore isn’t a Founder. Sisko agrees to release the new Changeling, but into Odo’s custody.
The newcomer, Laas (if he sounds familiar, it’s because he’s played by J.G. Hertzler – General Martok), says that he understands the Founders’ distrust of humanoids but doesn’t understand why they would want to conquer them when they could simply be avoided. Laas has been around for 200 years, compared to Odo’s thirty, and is much more skilled at shifting form. Odo says that humanoids are more tolerant of differences than Laas believes, but the latter is not convinced. When Odo introduces Laas to his friends, it does not go well – Laas really does not like humanoids and makes no effort to be nice to them.
Laas says that being on the station is causing Odo to deny his own nature, and he needs to be with others of his kind. Not the Founders; Laas says they should look for the other members of the 100, and make a new Link. Which is tempting for Odo. Laas does not make friends on the station and matters deteriorate, resulting in Odo examining his own actions to see if he is being stifled by humanoids, as Laas says, and tolerated simply because he assumes their form.