Easy way to find out if this wall is load bearing? (double top plate, but parallel with trusses) with pictures
I see rafters in your pics, not trusses.  Regardless, in general, you are right that bearing walls don't normally run parallel to the rafters. If it were load bearing, there should be a kneewall (2X4's) built from the rafters or a header down to the double plate you spoke off.  Also, in the basement level, you would see a beam with posts to the footers directly under the subject wall.  The only unanswered question I have is, if the addition roof is being supported to that wall? I do see in your pic a small knee wall from the rafters to something below, but not sure if that is part of the wall you want to remove.  Summary, if there are not structural supports going from the rafters to the double plate of the wall you want to remove, it most likely is not a supporting wall.