Giselle is a porn actress. She first appears in Blood Rites.
In the series
In Blood Rites, due to the Malocchio curse, Giselle was scalded in the shower and fell through the glass doors onto the electricity-laced flooded floor red with her blood. When Jake Guffie tried to save Giselle after she screamed in the shower, he walked through the electrified water—both he and Giselle were electrocuted until Harry Dresden jinxed the power. Jake and Dresden teamed up to do CPR on Giselle, who was unconscious and severely cut and burned, till the EMTs arrived. Dresden felt the curse before it hit, it's how he got there in time. He gave his car keys to Dresden to give to Emma.