Some dark instinct led her, and she didn't question it.

It saw dazzling scientific achievements - and the darkest human instincts working on an unprecedented scale.

Doyle, reverting to his darker instincts, tugs tentatively at the cord.

I'd like to see him yield, essentially, to his darkest instincts.

But if "To Be Torn" is anything to go by, she should trust her deeper, darker instincts.

It's when they get into bed with each other that their darker instincts take over.

When he fully comes into his powers, his dark instincts start to take over.

But some dark instinct drew him dragonward.

Looking at the moving neon woman astraddle the door, Jack thought that maybe some people arrived here simply by following their darkest instincts.

Perhaps the blood weed, driven by some dark red instinct, had learned to use such pits as a trap.