Just because they are "good" doesn't necessarily mean they aren't impulsive or don't have opinions or views they aren't willing to fight for.
A copper dragon makes its home in an area (desert, forest, wherever) and considers itself to be a protector of the area. PC's stumble through while on a quest and start killing any dangerous looking creature that approaches them. The dragon sees them as trespassers and vandals, they even killed a creature it was particularly fond of and considered a pet. Breathe weapon first, ask questions later.
Or a good aligned creature may be doing some shady things "for the greater good" - because they are impatient with how long it is taking to accomplish by legal means. Or because it's easier than dealing with the paperwork. The PC's may be hired to deal with them.
A good aligned "trickster type" creature may target the PC's for pranks or thefts in order to get them to pursue it - and then lead them into an evil organizations lair or camp so the PC's will fight the bad guys. Why doesn't it just ask them? Because it doesn't trust people to be altruistic.
A copper dragon makes its home in an area (desert, forest, wherever) and considers itself to be a protector of the area. PC's stumble through while on a quest and start killing any dangerous looking creature that approaches them. The dragon sees them as trespassers and vandals, they even killed a creature it was particularly fond of and considered a pet. Breathe weapon first, ask questions later.
Or a good aligned creature may be doing some shady things "for the greater good" - because they are impatient with how long it is taking to accomplish by legal means. Or because it's easier than dealing with the paperwork. The PC's may be hired to deal with them.
A good aligned "trickster type" creature may target the PC's for pranks or thefts in order to get them to pursue it - and then lead them into an evil organizations lair or camp so the PC's will fight the bad guys. Why doesn't it just ask them? Because it doesn't trust people to be altruistic.