How to create textured objects that blend in with the background in Illustrator?

Question

Ok, so the question by itself might be a little confusing, but basically, I've been banging my head against the wall trying to figure out how to create something like this:

Or something like this:

What I want to achieve is to create a texture on an object in Illustrator, so I can blend in the object with the background and give it more depth. In the second example, pay attention to the shadow on the face. It's kind of like a shadow gradient, but it blends with some grain into the full face, and I love that effect but just don't know how to achieve it, or if it has a name to look it up.

Your help will be greatly and amazingly appreciated :D

Answer 1

This sort of fine texture is difficult to synthesize in Illustrator alone. I think this could be achieved using Photoshop more easily.

But, the Brush tool in Illustrator can produce something similar to the shadowy gradient effect in the second image.

I've created new brushes and shown what some of the dialogues look like. I believe with some experimentation you might be able to get what you're looking for.