Your Friend Will Hide Away, If Light Will Not Display

Question

Riddle me this:

My counter has a speed,
And loves to play with fire.
The set becomes my seed,
When twinkles then respire.

I am not transparent,
My leading property.
I might not look so pleasant;
The more, the less you see.

My friend is also yours;
It follows all the time.
The one rule it ensures,
Is that you are its prime.

Attached, it never leaves;
It holds on tight 'til end.
I am dressed by thieves,
When crimes will impend.

What am I?

The first half is about myself, and the second half is about my friend, even though our friendship is not very light.

Note: I have included the wordplay tag, but there is not too much wordplay.

Answer 1

Is the first half

Darkness

And the latter half?

Shadows

My counter has a speed,
And loves to play with fire.

The opposite of darkness is light, and it travels at the speed of light. Light is an integral part of what makes fire

The set becomes my seed,
When twinkles then respire.

I believe this is referring to the sunset. Twinkles typically refer to stars. So when stars respire or set, darkness comes.

I am not transparent,
My leading property.

Darkness's leading property is that it's opaque or black. The point of darkness is that you can't see clearly.

I might not look so pleasant;
The more, the less you see.

Darkness can be scary, especially because you can't see anything. The more darkness there is, the less you can see.

Is the latter half of the riddle referring to

A shadow?

My friend is also yours;
It follows all the time.

Shadows are attached to you and are ever present.

The one rule it ensures,
Is that you are its prime.

Shadows always originate at the person's feet, hence it's prime.

Attached, it never leaves;
It holds on tight 'til end.

Again, shadows are attached to people.

I am dressed by thieves,
When crimes will impend.

Crimes are often committed in the dark (shadows), and shadows are used by criminals to hide their misdeeds.

The first half is about myself, and the second half is about my friend, even though our friendship is not very light.

Both are pretty much the opposite of light, but are compliments (friends) to each other.

Title: Your Friend Will Hide Away, If Light Will Not Display

The friend here, as mentioned, is a shadow. If there is no light, there can be no shadow either, only darkness.

Answer 2

Continuing with Joe-You-Know's second half, is it possible that you are

The Sun?

My counter has a speed, And loves to play with fire.

The Sun is made of fire

The set becomes my seed, When twinkles then respire.

After sunset comes the twinkling of other stars; but after the twinkles are "finished", the Sun is reborn (ie. seed) in the morning.

I am not transparent, My leading property.

Even though it is gaseous, it's not transparent

I might not look so pleasant; The more, the less you see.

The more you stare directly at the Sun, the blinder you get

This would tie in nicely with Joe-You-Know's answer, since

The Sun creates shadows here on Earth; the shadows aren't very light indeed!