"I haven't read anywhere about such encounters," Al confirmed, but clarified. "Yet, at least."
Plato froze as well, for awhile. He pretended to be long-dead, and dry, hanging onto the thicker, greasier hair strands that he was used to, but then his curiosity won over as he began a long trek upwards, occasionally checking for bookworms or other sustenance along the way.
"You smell like books," Al reassured Severus, watching Plato take his cautious steps, undoubtedly picking up deeper nuances of dusty, stale, familiar scent by every move the spider made with each one of his eight legs. "He'll like it."
Plato won't mind the feather taste as well. I've introduced owls to him before.