Trillium is the only one of her kind, or so she thinks. But there have been a few mentions of a being like her so far. Others have seen a Trillium-species individual before.
But she is unique. The other’s of her species are, in fact, time-traveling versions of herself. She gets mixed up in the time stream at some point, and ends up wandering around her current world-line. But not too close — without protection she can’t directly interact with herself, the paradox effect creates an increasingly strong repulsion if she were to try. Not sure what the protection would be.
In fact, she is a mythic figure of the Ancients, or will be in her own time-line. But that’s after The Event. The Event will eventually make her character unplayable, and requires a lot of build-up. I’m not sure what it is. But she is thrown far back into time to stop the evil which now threatens the multiverse from having already conquered the multiverse an age ago.