Why do some dialogue options have percentages next to them?

Question

I noticed that some of my dialogue options have percentages next to them. Here's an example:

Not only does it have a percentage, but also an icon and it's highlighted green. What's special about it? What will happen if I choose this option?

Answer 1

It is the chance that you will succeed at that dialog option (such as getting some extra money or items from the NPC).

Points in the Persuasion skill raise this chance.

I haven't run into any negative side effects with attempting and failing these sorts of checks, other than the fact that you don't get whatever bonus they would have given you, and you can't try again.

Answer 2

Some dialog choices end with automatically selecting a secondary 'bad' choice. One example is when you meet up with a certain person. You can let them go free, fight them, or get a chance at making them pay you and let them go free. If you fail to make them pay you, you fight them instead of getting another chance to let them go free.

Answer 3

This is one of the most entertaining parts to watch. This requires skill points added to the persuasion category. Under some circumstances you can circumvent multiple fetch quests. Also, some situations will only allow a bad option or a persuasive option. Without the persuasive option being successful it is impossible to get the bonus or positive effect. The only way to get to the points where you either have a bad option or a persuasive option is to talk to individuals and hear what they have to say about every subject. Eventually a subject will start a quest opportunity that requires a solid persuasive skill. The easiest example is when you get to mel senshir for the first time. On the way to fighting Ballor you have an opportunity to speak with a knight. Select the option "join me" and the opportunity will come up to persuade him to. If you fail he will not join you in the battle. There are others I cannot recall at this exact moment.