When her powers first manifested after the cryogenic accident in her brother's lab, Christine found that she turned people into ice with a touch, and in some cases, at short range.  The accident and chemical reaction in her body left Christine with an aura of intense cold that surrounds her constantly.  Before she began to hone her powers, the aura would instantly turn anyone or anything she touched, or in some cases, just remained close to, to solid ice.  Now, with a little more practice, she has honed her powers somewhat to the point that by concentrating, she can interact with objects and people for extremely short periods, such as say, giving a handshake.  Although such an act is often uncomfortable for the person she touches in that manner, it is not instantly transforming, unless she wills it, or the momentary touch/closeness is extended.  

When a subject does undergo transformation to ice from Frosteen's touch, however, they-- from what little has been pieced together-- are apparently placed into a state not unlike an enforced state of suspended animation.  Unliving objects, however, are merely frozen as though they had been dumped into liquid nitrogen; they are very often made brittle and easily shattered.

That is not Frosteen's only means of offense, however.  By drawing upon the aura of freeziness around her, she has also managed to learn how to concentrate it into beams of power that at close range have much the same effect as her touch, and at further ranges freeze the moisture in the air, giving her the ability to coat people and objects with ice.  How expansive this facet of her powers is has yet to be revealed.
 

If the Junior class of Hub City's Westfield High School would have taken a poll entitled “Least Likely to become a Super Villain,” Christine Mueller would have topped that list.  The shy, small, timid girl was not very well known, but those that had any passing knowledge of her knew that she was never one to act out any angry impulses she might have had.  Or even talk much, for that matter.  Through three years of high school, Christine was such an introvert that a good cross-section of her junior class didn't know anything about her beyond her name.  In fact, the only other person who really knew her at all was her older, college-bound brother Michael. 

Christine had always looked up to Michael.  He was already making headlines for his patents and inventions, particularly in the field of refrigeration and cryogenics.  He already had a goal in life.  People in school knew who he was... he wasn't afraid to make his opinions and thoughts known.  He was always open and friendly to her.  People, including herself, liked to spend time with him.  In many ways, he was everything she wished she was.  But the hero worship she had for her brother never crossed the line into outright envy or jealousy.  Christine merely wished that someday she could be like him.

One day, Christine went into the lab he'd constructed in the basement of their house for his work, mostly just to see if he was there and spend some time with him.  While inside, though, she accidentally knocked over a test tube, which caused her not only get some sort of chemical combination all over her, but to jump back from shock and trip.  She fell into a nearby pod-like machine, and once she entered, the door shut and the machine hummed to life!  The yet-unfinished cryo-pod reacted to the refrigeration chemicals on Christine’s body...

Later, Michael returned to find his sister huddled in the pod, shivering, so cold she could not move.  He quickly rushed to her aid, reaching down to lift her to her feet...but upon doing so, the terrifying truth was revealed.  Not only was Christine’s skin dangerously pale and her hair turned blue, but upon touching the hand of her brother, Christine could only look on, horrified, as her brother slowly changed into ice!  A look of terror remained frozen on Michael’s face, and Christine panicked, stumbling out of the lab to try to get help.  But everyone she touched-- or in some cases, got near-- proved to be no help, as they too turned to ice!

All the panic soon drew attention of the local defenders of Hub City to the ordinarily quiet suburban neighborhood.  But by the time they arrived, Christine was beyond reason and out of control.  Several heroes were frosted before the teen finally managed to escape, and the costumed crimefighters saw to their frozen number. 

It took a long while, but slowly, Christine managed to find the courage to make her way back to her brother's lab, only to find it empty.  The icy statue of Michael was nowhere to be found.  Unable to face her parents, and guilt-ridden over what happened to her big brother, Christine left her home once again.  She was left alone and very, very cold.  It was a bright, mid-summer day, yet she huddled in her parka, snow boots, and goggles, struggling to keep warm.  And while doing so, all she could think about was one thing.  It was her fault her brother ended up an icicle. 

No... She had tried to get help.  But the heroines...they wouldn’t listen!  Thanks to them, her brother was gone... he could be melted now, for all she knew, and she could do nothing about it!  It was all their fault, her mind finally concluded. 

And somehow, she also decided, she would find a way to make them all pay. 

Frosteen's personality still shows a slight semblance to Christine's shy, introverted nature... but where Christine once tended more toward polite shyness, it has since become a sort of cold standoffishness.  The soft tone of her voice now feels more like a sibilant threat rather than the hesitant mumble of an awkward teen.  She doesn't like people-- pretty much on the whole, and isn't afraid to show it-- but has a particular antipathy toward costumed heroes and heroines.