Nice! He (?) doesn't look very hostile to me; how smart are the mere dragons?

Fairly smart. From what I recall all true dragons on Mhar are fairly intelligent and some are spell users and shapechangers. The mere dragon is certainly cunning. In one game we came across a young one that was thin and limber enough to crawl into people's houses.
Its the wyrms that are the stupid ones in the family tree. Wyrms are sort of the mutant hybrids that spring from by-blows between the five different species of dragons. Good thing for folks most wyrms are sterile since they are slightly more common (relatively speaking) than dragons. That is, except for the wyvern which is a hybrid between High Dragons and Mere Dragons. Those little buggers aren't sterile and been happily making little wyverns. They may be the weakest of the dragon-kind on Mhar but one was still enough to decimate our party.

nice ^^ draw and details are cool