Generate a detailed portrait of Grigori Rasputin, emphasizing his real historical appearance. Include his intense, piercing blue eyes, long dark beard, and shoulder-length hair. Ensure his face is rugged with a slightly gaunt, weathered look, and capture his stern, enigmatic expression. Dress him in a simple, dark robe typical of early 20th-century Russian attire, with a neutral or slightly worn background to highlight his presence. Use realistic, high-resolution textures and shading to bring out the intricate details of his features and clothing