Oooow... His face is just terrifying in that scene. That moment when you realize that after all he's been through, he is NOT going to throw the damn Ring into the fire... And when he turns to Sam, with that purely evil look in his eyes - "The Ring is mine."... Nooooo !
The pink around his eyes really exhibits his exhaustion. Also, he's got that look of... deep thought and concentration. Like he's trying to make the right choice of something. You're art is great! I love it!