Odo bugged me a lot because his sex was a total fabrication, and though he did link with Laas, another "male" Changeling once, the other two relationships that I remember were with the "female" Founder and the biologically female Nerys. If any character should have been pansexual, omnisexual, or even asexual, it was Odo, but he was depicted as heteronormative as the rest of them