Tanis’ eyesight vs Flint’s

Flint squinted into the gloom. “I don’t see anything.”
“I did,” Tanis said. He kept staring at the place where he’d seen the metal, and gradually his elvensight began to detect the warm red aura cast by all living beings but visible only to the elves. “Who goes there?” Tanis called.

Excerpt From Dragons of Autumn Twilight, pg 33
Margaret Weis & Tracy Hickman