Haven't figured out why this isn't working and would still really like to know, but I did at least come up with a workaround, so thought I'd share. As best I could understand it from looking at how the Vanilla followers were setup, the IdleChatter topic has a list of random one-liners with a non-random line at the top that has no text or voice data and has the condition GetRandomPercent <= Global Variable FollowerChatterPercentage. Then there is SOMETHING (can't find what) that is telling the NPC to speak their IdleChatter line. When that happens, it first hits the non-random empty line, which basically rolls the dice and 75% of the time will speak the empty line, which has the effect of seemingly nothing happening in the game. The other 25% of the time when the non-random line's condition is NOT met, it gets passed down to the random lines, one spits out and it has the effect of the NPC spouting a one-liner. What I couldn't find anywhere was WHAT was calling the line, but I got around this by adding a GameMode script to my dialogue quest that effectively does this: continuously fires the IdleChatter line with a success rate of 25%. Rather than having the empty line of dialogue, I just built the whole "if GetRandomPercent > FollowerChatterPercentage" into my quest script because it seemed more efficient, but I'd still like to know the proper way of doing it, because I would think the vanilla followers are setup in a more efficient manner than a "sayto" line that is constantly firing...