Paul Dini created Harley Quinn and in "Mad Love", together with artist Bruce Timm, he writes the origin story of the character where we find out she was a psychologist at Arkham who fell for the Joker's charms in a Stockholm-syndrome kind of way. The "other stories" in the title feature a variety of villains such as the short-lived "Roxanne `Roxy Rocket' Sutton", a jewel thief who flies around on a rocket with an old-timey ray gun, the Ventriloquist, Scarecrow, Catwoman, Two-Face, Poison Ivy, Clayface, as well as Ra's Al-Ghul, Talia, and Etrigan who feature in the second long story arc.
The book is great fun to read and, as a fan of the animated series from the 90s, it felt like I was reading episodes from that series, especially as Dini and Timm basically ran that series for years. Harley Quinn is a fine villain and has developed into a more interesting character over time but it's still good to see where it all began and "Mad Love" is a must-read for all Batman fans. Just don't expect the overly dark Batman of today in this book as the stories are cartoony and light (most of the time).