Mary trained very hard and became, in time, one tough woman! Not only was she deadly from afar, she could easily get in and grapple her opponent, leaving almost no bone unwrecked. Blue Mary then got her chance as a secret agent at a very young age. There is where she met what she thought at the time, was the man of her life. His name was Butch (why do I always picture a bulldog when I hear that name?).

Blue Mary and Butch worked together in several missions, sucesfully completing each and every one. They got to know each other more and more after every mission. Mary was charmed by Butch's lovely attitude, his will for doing the job well done, and most of all, his will to live. Butch was also very impressed with Mary, since he had never known a woman so tough and decided as her! Soon, Mary and Butch began to learn a lot about each other, and both were very happy with each other. Mary saw Butch as a man who would never surrender until he got the job done. She admired him for that. Once, when they were drinking at a bar, Butch got up, stood behind the barstool, and began to whip out a drink. After it's completion, Butch named it the "Blue Mary", his favorite drink, and something he would always rely on. Thus, that's where the name Blue Mary came from.

One day, Butch was assigned a very precarious mission of high risk. Mary offered to accompany Butch, but he refused, excusing that Mary was still not up for the job, and that it was for her own sake. With a tender smile, Butch bid Mary farewell, and went out to complete the mission as soon as possible. Mary waited for days, for weeks...and Butch never came back...and he never did.

Finally, Mary received from a member of her agency a leather jacket. It was Butch's, and it was found right in the place where Butch had died. Mary took the jacket, and still puts it on, reminding her of her love for Butch. Mary then realized she would complete Butch's mission: that of erradicating the scum of society and wipe them off the face of the earth.

Mary soon began even more popular than Butch. Her missions were always realized with quickness, and efficiency. She always had a way to get things done, always at her way. Mary, and her pet dog, Anton, traveled the whole world, cracking cases and trapping the bad guys. However, in one mission, she discovered a very serene man who was fighting once. Mary distinguished him as a strong man with long, blonde hair, and a trademark red cap. After finishing his battle, the man took a look at Mary, and recognized her as a pretty tough woman. Mary laughed, and ever since, the man and her have been very close friends. The man was no other than King of Fighters legend, Terry Bogard, the man whom defeated Geese and Krauser.

As of late, Mary has began being more and more involved with the Lone Wolf. She was amazed on so many experiences Terry had ever since his father died at the hands of Geese Howard. Mary found a lot in common between her and Terry, and she was beginning to feel something she had not felt for a long time. Something she had not felt ever since Butch was with her. Mary was truly enchanted by Terry, and she began to fall in love with him.

However, her work was far from over. One day, a secret person, in charge of a personal investigation agency, sent a letter to Mary for a secret meeting. Mary attended the meeting, and the person was there, waiting for her. The man told her that soon, Ryuji Yamazaki would be entering the King of Fighters '97 tournament. Mary was familiar with Yamazaki, who was reknown as a very infamous gangster. The mystery man told Mary to keep an eye on him and Billy Kane, who was sent by Geese to look after Yamazaki as well. Mary's suspicions grew more and more: what did Geese want with Yamazaki? Without any other clue, Mary teamed up with Yamazaki and Billy, forming one of the more peculiar teams of the tournament. During the outcome of the tournament, Mary discovered, from Yamazaki's reactions to the manifestations of the Orochi power, was that indeed, Yamazaki was of Orochi blood! Mary was surprised, and figured out that Geese had sent Billy in order to keep an eye on the Orochi power of Yamazaki. But, then, what did the mysterious man want with Yamazaki and his Orochi power? This became very suspicious for Mary, but during her moment of confusion, Yamazaki had run away.

With no other cue more than to investigate the true intentions of the secret man, Mary began a new case. She soon found out that the mystery man was working for Geese Howard, and that he was using her to aid Billy to control Yamazaki, and bring the gangster to him! Mary was enfuriated, and taking a new case in her hands, Mary went out to catch the most powerful man of Southtown.

After two years of being on the trails of Geese Howard, Mary received a surprise invitation by King, one of her contacts in Southtown and personal friend. She was asked to join King in the latest King of Fighters tournament. Thus, Mary decides to leave the case temporarily, and helps her friend out. After all, it's always time to have some fun breaking some bones!

Ever since Mary became aware of the existence of the NESTS cartel at action in the King of Fighters tournament, Mary now directs all her attention in investigating the whereabouts of the evil organization. Upon futher inspection, she finds out that NESTS is now very active in Southtown: her own hometown. She decides to join the Lonely Wolves and her beloved Terry in order to warn them about the evil at work in their own turf. To this end, Mary has a new purpose: to stop the NESTS cartel ay any cost!

After the matches ended, Mary urges Terry and the others to hurry to Southtown, as NESTS might already be formulating another twisted plot. Upon arrival, Mary's contacts inform her about some suspicious actions taking place in the factory zone of Southtown. Mary leads the Lonely Wolves into the abandoned industrial district, where they suddenly find a factory surrounded by soldiers. Mary warns Terry and his friends about the danger, and is futher confirmed when the soldiers begin attacking the intruders! Mary uses her police- honed skills to stop the NESTS agents in their tracks. But the sheer number of soldiers down their throat is so intense, Mary and the others are forced into the building itself.

During the fight to survive, the whole building begins to shake, and the soldiers escape hastily. Mary makes a soldier cough up the truth: the Zero Cannon has just fired, and is now directed towards Southtown. The previous shock of the Zero Cannon blast makes the building begin to fall, and one fallen rock knocks Terry, wounding him. Not ready to give up her beloved one again, Mary hurries to help Terry, but Terry tells Mary that she won't be any good for him if she dies here. Mary, reminding Terry's sheer will to survive, escapes along with Andy and Joe.

After the complete destruction of Southtown, Mary's rage towards NESTS now knows no end. She begins to scout the areas around Southtown in hopes of finding out about NESTS. The several thugs she meets doesn't giv her any useful info. In a police hunt at a local criminal hideout, Mary violently wishes to punch the truth out of the thugs. She finds no answer, but she does feel that somebody is following her. It turns out to be Terry! He's pretty much alive, and on her way out, Mary promises Terry that she'll take care of NESTS for good.

Using her superior detective skills, Mary has managed to find out that NESTS is finally going to go public at the next King of Fighters tournament as the new hosts! Mary finds is surprising that NESTS would reveal themselves and cast away their disguise after they had just totalled Southtown, but the only thing she can think about now is to inform Terry. Terry tells Mary that the sins of NESTS will not go unpaid. He offers Mary to help him once more to deal with NESTS once and for all, and Mary isn't the woman to back out of a case!

During the fights in the tournament, Mary begins to realize something very important: even though NESTS has brought everyone lots of despair and suffering, and their actions could not be forgiven, she owned them the pleasure and honor of being able to team up with her beloved partner: Terry. Throughout the last years, Mary and Terry, more than fighting together, have lived more and more experiences as a couple, and Mary has been able to find more attributes in Terry than ever before. After the end of the tournament, and after NESTS falls to its' destruction, Mary and Terry have a whole new life to see in the future, together....

Mary is a very spirited young woman, and since she is pretty well known of how men fall for her beauty. She even exploits her enchants to make her fights more easier! She is as gracious as a rose, but also with deadly throns. Once in a while, Mary feels a bit lonely, that's when she begins to sing a blues. However, Mary is also a very dedicated woman, who has no other vision in mind than to complete her mission, and trash the bad guys!