Paths: what is this?

I am trying to apply an 'artistic' brush stroke to a path but it treats every intersection like a whole new path and starts the 'taper' effect at every intersection [see image]. I want the line to be solid, only the ends are to be tapered.

Question:

1. What is happening [noob to Illustrator]?

2. How do I fix it?

Paths: what is this?

An ArtBrush cannot ''wedge'' around sharply angled cornerPoints. Looks to me like you are seeing its attempt to miter at corners. Do this:

Get the Rectangle tool and draw a rectangle.

Get the Ellipse tool and draw an ellipse.

Apply the same ArtBrush used in your example to both of those paths.

Both paths have four anchorPoints. But the rectangle has corner points while the ellipse has smooth points. You'll see the ArtBrush try to ''miter'' itself around the corner points. Now select the rectangle and apply the Round Corners Filter (or Effect) to it with a small ''radius'' setting. That will likely improve the bending around the former corners.

Also, your description seems to imply that you think two paths which form a tee (lower left green circle in your screen shot) can be the same path. They can't. Each anchorPoint has no more that two associated segments. (This is different from Flash, if that is what sets this expectation.) There is no way you can have an intersection like the one referenced and have it actually be a single path. (The two paths can be subpaths of a Compound Path, but strokes or Brushes applied to them still won't behave like you seem to expect.)

JET