and I am assuming he slept with Mirror Kira lol
I got that impression as well.
While we're talking about the logistics of the symbiont, I have always wondered how they reproduce. I'm assuming that Trill hosts have the ability to get pregnant much like other humanoids ("Facets," "Tears of the Prophets,") but how do they make new symbionts?
And who in the world was the first Trill to even come up with joining?? Can you imagine that conversation, "Hey, you know those slugs that live in the pools underground? I wonder what would happen if I put one in my belly..."