I like the Listener. I have the urge to write a sga/listener xo, where Toby is Patrick Sheppard's illegitimate son. John Sheppard goes to Toronto with Rodney to a science conference. There's a mishap at the con (heart attack or something). The paramedics respond to the call. And John can hear Toby instinctively trying to cajole the heart attack victim. In the main, Toby's abilities seem pretty passive; he listens rather than projects. John's really locked down (there's a surprise) but suddenly there's a telepath in the vicinity projecting to whom he's related.

And then I kind of stall... It all relates to the ATA gene of course.