Deanna isn't even in Starfleet the first time she meets Will Riker. He's come to Betazed on assignment, and she's asked by her mother to be his personal liaison, help him become acquainted with the planet, keep him out of trouble. The trouble, it would seem, would stem from Deanna's mother herself, whether in mind or body far too much for the uninitiated to handle, and even for those who have known her for years. But it's more so that he won't notice everything else that's wrong with the planet.
Which is to say, everything.
To put it mildly, Betazed's best years are behind it. By the time it was awarded membership in the Federation, it was a planet in cultural decline, so in fact the only reason it petitioned in the first place was to try and recapture some of the old glory. Because there are no secrets on Betazed, and this has become a problem.
You see, Betazoids are empaths. They can read and project thoughts at will, speak through each other's minds, and generally get along with a level of intimacy that would be unsettling on any other world. Deanna's mother is the prototypical Betazoid. As the leader of the last of the great houses, Lwaxana Troi took it upon herself long ago to do everything in her power to reverse the decline. She lives in defiance of the truth, and is happy to do so, by the way. After all, there are no secrets among Betazoids.
Which is why Deanna's father was human, totally devoid of all Betazed's gifts, the reason Deanna herself can only sense emotions rather than thoughts (although among her own people she remains perfectly telepathic). The idea, her mother quickly seizes upon, is to build on the initial attraction Deanna can't possible hide from her concerning Riker. It's obvious to everyone, even the other species Betazed has made a state policy of enticing to visit and if at all possible stay forever.
Yet Deanna hasn't just fallen in love with Riker, she's made a critical decision. She is going to leave Betazed forever. This is the opposite, actually, of what her mother hoped to achieve, the idea being to make it better, easier, for people to stay.
Yet, more and more, they aren't. The younger generations have taken all the wrong lessons from what their elders have tried to accomplish. They're forgetting Betazed. On a world like this, memory is everything, and losing anyone is to lose a part of everyone. Lwaxana Troi especially.
Fortunately, she has a few tricks up her sleeve. Betazoids are among the cultures that still believe in arranged marriages, and Deanna had hers in order a long time ago. She's just experimenting, or so her mother believes. All that's about to happen is harmless, really. Nothing to worry about at all.
If need be, Lwaxana Troi will rescue her daughter, and if she can't dissuade her from this career in Starfleet that is suddenly more interesting than even Riker, then she will follow Deanna into the stars. She's been there before. What could possibly go wrong?
She doesn't attempt to keep any of these thoughts from her daughter, but Deanna is constantly distracted, the kind of girl who concerns herself with ideals more than reality. What kind of Betazoid is that?
Maybe there ought to be some secrets after all...