Vanilla JavaScript hovercards for author links. While a page renders, LH Hovercards collects the author URLs and author archive links that appear in the content and maps each one to its user. In the footer it prints the mapping and a hovercard template per user, and enqueues a small script that shows the card when a visitor hovers over a mapped link.
It is currently limited to the super admin (user 1) while in development. Themes can override the card markup with lh_hovercards-templates/hovercard.php in the stylesheet directory, and filter the mapping with lh_hovercards_return_mapping_array.