Gran doesn't know why he does it.
All he knows that when he pushes just right, presses the buttons that really hurt, there's a flash of something in Vane's eyes that sets his smile sharp and sinister, the flash of his teeth a snarl - a challenge to back off before someone got hurt.
Gran loves it.
It probably began when they found Lancelot. Poor Lancelot, Lan-chan, beaten and trussed up in rusted chains. It's a sight that sends even the normally scathing Percival into a chilling silence. Normally Gran would appreciate that more, and he does indeed turn to subtly memorise Percival's expression, but then he sees it. Vane, oh Vane, his expression something that Gran's never seen before - there's a darkness, a wild brutality in his eyes, a dangerous edge to his smile and a restrained fury in his voice that sends a shiver of pleasure down Gran's spine. The urge blossoms then - the urge to see it again, to see that gaze directed at him, teeth bared so close they could tear and rip into his flesh.
Gran shivers again. Oh yes.
"Captain, what is your problem?!" Vane hisses, all semblance of politeness abandoned, discarded like the soldiers lying still in the clearing to their left. Gran zones out a little as he savours the fire behind Vane's words.
He vaguely realises that Vane hasn't stopped his tirade, scolding him for his reckless actions with a voice filled with the anger that Gran loves. He's beautiful like this, Gran thinks absently, fingers twitching at the urge to stick them between Vane's clenched teeth. Would he stop, surprised? Splutter?
Or would he bite down?
In the darkness of the night, Gran finds that sometimes his inhibitions loosen. Maybe that's why the words slip from his mind, tumbling quietly into the crisp night air where he sits, Vane quiet opposite him.
"I'd let you hurt me, you know. I'd enjoy it."
For one moment, one shudder of Gran's heart, their eyes meet.
The look in Vane's eyes is hungry, ravenous. Gran's breath hitches, fight-or-flight instincts kicking in as he unconsciously leans further back, the overwhelming sense of danger, danger, predator, run, hunger overwhelming him, sending delicious pleasure rushing through his veins because he meant it, he'd let Vane drag him down to the ground and tear him limb to limb, rip his throat out, crush his heart, if it's what he wanted-
"C'mon, Cap, you can't joke around like that! It's dangerous, you know? What if people get the wrong idea?" His voice is concerned, eyes filled with warmth as they flick worriedly over Gran's face.
But when Gran graciously accepts defeat, the both of them laughing and joking as they return to the ship, he feels eyes on his back the whole time. Burning.