Catwoman Body Swap Gone Wrong by Jeffapr202006 (Archive Link)
With this Catwoman story by jeffapr202006, the FBI agent Samantha goes through some very experimental process to switch bodies with the notorious criminal, Catwoman. Trying to get more information about the actual identity of the woman under the permanently locked on latex suit, as well as trying to find out more about the general criminal underground, Samantha only has one chance to switch back, as there was only one of the machines making this entire thing possible. But most importantly, only two people know that Catwoman was actually Samantha now, so basically everyone thought Catwoman escaped.
Notes / summary for me (SPOILERS!)