Sneak after Annamae

You sneak after Annamae, curious.
She moves behind the barn and you soon realize she's meeting with someone
As you sit to watch, you notice that the person she's meeting with is somewhat familiar.
You may have not been introduced, but you can recognize him from the pictures in the farm.

It's Clarence, Annamae's brother.

Surprised, you sneak closer, moving around a tractor, and see they kissing each other.
Both look around and move behind the tractor, a few steps from you, and you now have a great view.
You're so close you can see Annamae put her hand inside his pants.
And the night it's so silent you can hear they talking.

Annamae's is complaining to her brother that he went out with a city girl named Rachel and how he doesn't need any other woman except for her.
You can hear when he mocks and asks Annamae if "that includes mom too?" and you can see as she slaps him. He puts his hand into her pants and now they are both teasing each other.
But Annamae isn't happy with him and keeps complaining about Rachel and as you listen you figure out that she and Rachel fought over him...

And Annamae lost.

Now they are half-naked behind the tractor and passionately kissing, and while you can feel the cold of the night they don't see to bother.
Annamae pushes Clarence down and start to ride him, cowgirl style, arguing she rides him best, but Clarence mocks her saying she couldn't even ride Rachel.

Angry, Annamae starts to bounce up and down on his cock, shaking and moving her hips, and you are impressed with her skill and stamina.
But her brother doesn't seem that impressed and keeps teasing her even as she exhausts herself on top of him, mocking her loudly. Still, you can see him getting closer.
You get the feeling that they are playing with a game with each other and will keep this up until one can't take it anymore and cum... but you know that this won't last much longer.

You can either watch to the end or reveal yourself.
Or maybe you could take some pictures?
That's when you hear a noise.

Shit, what you do now?