I think the insinuation in Nightwing/Huntress was that Helena slept with Dick to get closer to Batman,
Wow. That's not the impression I got. Her whole seductress thing, and the way she always talked about Batman at the time, I got the impression that she was wrongheadedly trying to drive a wedge between Bruce and Dick, like she could somehow have an ally in Dick if his dick was in her. It didn't help that she was shotgunning her bile about Batman in almost every appearance she made at the time.