Recently, through some talk on a roleplaying games forum about violence in games, my brain started thinking. One of the tracks it rode upon was the one where a lot of the quests, problems and assignments the player characters in roleplaying games get are clearly and easily solvable with violence. Then, at one point during walking from the station to school, a thought struck me. Potion ingredients. You see, me and my wife are reading through the Harry Potter books together (I've never read them before, and it has been a while for her) and I guess the end of the second book (The Chamber of Secrets) had stuck with me. I'm not gonna spoil it, but those that know, know how it applies.
I was thinking how tears are not an easily harvestable ingredient from mystical creatures. You can't gather them by killing and skinning, like they are dragon scales or something. You have to go about it another way. And that made me think about why people might cry. It might be by telling it a sad story (like a thief's tragic backstory) or listening to a beautiful song (Bards and Disney Princesses, you're up!) or Priests and Prophets trying to instill guilt of some kind. (Clerics, Paladins, ... it's your chance). It's also a delightful chance for the roguish prankster players to think outside the box, like buying carts full of onions and start cutting them in front of the dragon. (Like many fairy-tale heroes.) There might still be those who might to use pain to make the dragon cry, but that gets into torture and X-card material and is clearly non-heroic behavior.
Anyway, I wanted to put these thoughts to words and get them out, so here are two ideas or story seeds to get this problem to your characters.