Origin

 

Katherine Reynolds was an assistant professor in Gateway University,  located in St. Louis, Missouri. When one of the university buildings started to show signs of strange  phenomena, scaring students and employees, she hired Daimon Hellstrom to investigate the source of the haunting. Hellstrom accepted the invitation, and after coming to Gateway he advised to Reynolds stay away of the haunted building while he investigated it. However, Reynolds would disobey this order while Hellstrom learned that the ice demon Ikthalon was behind of the supernatural incidents, causing to Ikthalon almost rampage on St. Louis and infuriating Hellstrom. Hellstrom later forgave Reynolds for her disobeying him, and let her assist him in the investigation of other strange cases around St. Louis.

Creation

Katherine Reynolds was created by Steve Gerber and Jim Mooney in 1974 and first appeared in Marvel Spotlight # 14.

Story Arcs

Together and with the help of other allies like priest student Bryon Hyatt, they stopped a satanic cult organized by a group of gullible students, stopped demonic snake Kometes from triggering an apocalyptic event, exorcized the demon Allatou from an innocent girl, saved one student of Reynolds of falling in the trap of an evil fortuneteller seeking revenge and fought against a strange sect called the Legion of Nihilists. When Hellstrom left St. Louis feeling his job in that city was done, Reynolds was uncapable to tell she had feelings for him.
 

In Legion of the Night

During the events of the short series Legion of the Night, it was revealed that, at some point, Dr. Reynolds had been abducted by a mysterious organization known as "the agency" and placed in a mental hospital in St. Louis, where the agents of this organization would conduct a series of experiments on Reynolds through drugs to amplify her psychic abilities, which were first seen in "Marvel Spotlight #22" where she used them to snap Hellstrom back from a state of coma. The length of the period of her imprisonent is unclear, but it is obvious that the abuse of the drugs, plus the abrupt development of her powers, ended up erosing her sanity, as she now speaks things incoherently, laughs like a maniac and develops a savage behavior on hand-to-hand combat. 

When Legion of the Night starts, she is seen in her cell having visions of an ominous event yet to be revealed. Later, she is strapped in a bed as rants non-sense things as keeps repeating the name " Fin Fang Foom", while the deity itself awakes starting a chain of apocalyptic events. She then uses her powers to escape from the hospital and gets Dr. Chan Luichow to join the other members of Legion of the Night. Together, they realize an assault against the fortress of Aan Taanu, the deity responsible for awakening Fin Fang Foom and starting the apocalyptic chain.
 
After the Legion is successful  in preventing Taanu's plans from destroying the world, she is seen lamenting that they won't get a "victory parade". Her current whereabouts are unkown, though it seems that she remained as a member of the Legion.