http://e621.net/post/show/21462/
This picture is drawn by Gravewalker.

http://e621.net/post/show/13623/
This picture is drawn by Rose Quoll, and features the character of Gravewalker.

http://e621.net/post/show/17184/
This picture is drawn by Micah Fennec, and features the character of Rose Quoll.

All of these together highlight the unfortunate problem that artist:blah and character:blah tags are singular, mutually exclusive, and retroactive as soon as they're declared as such. I noticed that middle one was tagged with artist:gravewalker and character:rose_quoll even though the picture is actually the exact other way around, so I tried to change them. Instead, it apparently just changed the default status of those tags, and set it so that now gravewalker=character and rose_quoll=artist, period, which of course messed up the other two examples. So I changed them back for now, and came here.

Perhaps something should be done about this situation?