At the end of Deep Space 9, Odo beams down to the surface of Cardassia to negotiate with the Female Changeling. She argues that
If I [surrendered], it would be a sign of weakness... an invitation to the Solids to cross into the Gamma Quadrant and destroy the Great Link. [...] The Dominion has spent the last two years trying to destroy the Federation... and now you're asking me to put our fate in their hands? [...] I can't do that, Odo. I don't share your faith in Solids.
In response, Odo asks her to link with him, and after a little cajoling, she does. Immediately afterward, she orders the Breen and Jem-Hadar to stand down and agrees to stand trial for war crimes. What could Odo possibly have told/shown her? It had to be something pretty damn powerful, since it would have been offset by the knowledge that the disease was Federation-created genocide. It also had to be something that happened (or he learned) since the last time they linked, when the Dominion controlled DS9.