Page "Odo (Star Trek)" Paragraph 8

Up until this time, Odo was unaware of his people and his ancestry.

A criminal showed him a necklace containing an apparently non-sentient shape-shifter in the episode " Vortex ".

Later, in the episode " The Alternate ", Dr. Mora visits Odo at Deep Space Nine and travels with him to the Gamma Quadrant to investigate a planet with a similar life-form.

It isn't until later that Odo learns that his people are the leaders of the Dominion.