In 1993, Andrew Wyeth invited Metropolitan Museum director Thomas Hoving to Chadds Ford, Pennsylvania for a two-session portrait.
(Link to video.) It ended up being perhaps the only time Andrew Wyeth was filmed in the act of drawing. Wyeth insisted that Hoving talk during the entire posing session because, first, he wanted to hear Hoving’s stories, and second, because he wanted Hoving’s face to be animated: "I must have animation," Wyeth said.
John Singer Sargent also liked his subjects to talk while he painted them. Vernon Lee told her mother that she enjoyed sitting for Sargent very much: “John talking all the whole time and strumming the piano between times...He says I sit very well; the goodness of my sitting seems to consist in never staying quiet a single moment.” They were childhood friends and she was as much a whirlwind talker as he was.
via Muddy Colors
Book: John Singer Sargent: Figures and Landscapes.