It’s been quite a while since I’ve done one of these posts, but it came up, I thought about it, and I want to make a post about it. By ‘it,’ I mean the Trill, and the Symbionts, as suggested by the title. This will be shorter than some of my past posts, as there’s only really one main point I want to make.
As usual, I make these posts because I think the general impression about them is wrong; or, at least, I have an alternate interpretation, that I think fits the fiction better than the general consensus. In this case, that consensus is that the Trill symbiont (the worm) merges its personality with the host (the humanoid Trill), which then makes a new person, so to speak. I don’t think that’s right.
I think that it’s more the symbiont is a repository of memory of the previous hosts. I question that the worm even has a personality, as we would recognise one. They are assumed to be sentient – the worms can communicate with each other in their natural habit, and it seems with hosts, and even caretakers of that natural habitat, to a limited extent. But, as I said, I don’t know if that means they actually have a “mind” as we would understand. And it seems that, even if it does, that doesn’t matter.
While the host’s personality – or at least, their external expression of that personality – does seem to change a bit, I wouldn’t put that down to a “merging” of sorts. Part of your personality, if not a large part, is shaped by your experiences – your memories – after all. If you suddenly, as a young person, gained the experiences of at least one entire lifetime, that’d change you. Just that would be incredibly valuable – and we (the viewers) can see that, with how the access to symbionts is controlled.
It also seems that the choice of hosts is not just based on intelligence and lack of metal illness, but on personality. As in, not much of one, at least by the time Jadzia was made a host. As we can see (and as we’d expect), Jadzia without the worm is far different from Jadzia Dax. But also, as we see from those times where we get to “meet” the past Daxes, each one is very different from each other. Jadzia just seems like a quiet, nervous nerd, but Jadzia Dax is pretty much the exact opposite. Presumably the future hosts are psychologically prepared on some way
And then there’s Ezri. She wasn’t chosen to be a host, she just happened to be there when a new one was urgently needed. We get to see, real time, what suddenly getting hundreds of years of memories does to someone who isn’t prepared at all. And it isn’t a sudden re-write of personality. It’s just an addition to what they already are.
(As an aside, I wonder if the conjoined Trill has eidetic memory. I don’t think the worm would work very well without it, but does the pair experience their memory like that? Especially if the Trill in general don’t, that’d be really weird to experience.)