Gamma Czarnecki is a student at Gunnerkrigg Court, and is Zimmy's best friend and girlfriend. She's Polish and does not speak English, which leaves her unable to communicate with most of the other students. She is one year older than the rest of her class.
Nearly one and a half year (one year and 102 days) before the events of Chapter 11: Dobranoc, Gamma she lived in the streets of Birmingham. That day, she met Zimmy for the first time and somehow clears her mind of the visions that plague her. After months of living on the streets with Zimmy, two employees of The Court comes and offer them the opportunity to live at the Court, but with freedom to go where they please, when they please. After some hesitation, the two girls accept the offer.
She is first seen in-comic helping Zimmy participate in a science fair, and later help Annie and Kat find out who's destroying the projects. Later, Zimmy and Gamma come to Annie for help. Gamma can only chase away Zimmy's hallucinations while she's awake, but she's very tired, and they need Annie to stay with Zimmy while Gamma rests. Apparently Annie's abilities have a similar, albeit weaker, effect on Zimmy as Gamma's. Just before a storm breaks out the three goes outside. When it starts raining the drops boils on Zimmy's head, resulting in her becoming very playful and a lot better mood and the black gunk around her eyes disappears.
The duo later comes up to the roofs of a building around The Power Station because it messes with Zimmy's head. There are other kids there, which they at first think are projections of Zimmy's mind. As they stand on the rooftop the station starts some sort of procedure where it drains the water in order to form clouds and then sends off an electrical charge into the horizon. Zimmy gets very disappointed when she realizes the rain doesn't have the same effect as it had before, her frustration builds up and she ends up in Zimmyngham with Gamma, Annie and Jack Hyland. Eventually Zimmy, Gamma and Annie gets out without damage, although, one of Zimmy's Whitelegs attach itself to Jack.
In her next appearance she seems to have some sort of hallucination, thinking that she's Annie walking around in Zimmyngham. When she sees how close Gamma gets to Annie, whom she thinks is herself, she snaps and remembers that she is in fact Zimmy. It then starts raining and they are all taken out of Zimmyngham, this time the rain does have the positive effect on Zimmy's mind and mood, as seen before.
Later, Gamma convinces Zimmy to go and help Annie, who is currently in the court hospital. After Zimmy wakes up and panics at the sight of Kat, Gamma is brought back in and then she and Gamma somehow disappear.
Gamma has an unexplained psychic link with Zimmy, which enables the two of them to speak telepathically in spite of their language barrier. (Zimmy doesn't know Polish.) Gamma also has a positive effect on Zimmy's mental state; when awake, Gamma's presence nearby makes Zimmy's hallucinations end. (It's unclear whether or not this effect is related to the psychic link between the two of them.) As a result, Gamma never leaves Zimmy's side, and she wears herself out trying to stay awake with her.
Oddly, while Gamma is quite introverted with the general school crowd (language barrier not withstanding), her telepathic feed to Zimmy is a torrent of commentary on everything around her. This might be related to the "grounding" effect she has on Zimmy.
Zimmy exploits Gamma's language barrier by "translating" other people's compliments as rude insults, hoping (and succeeding) to keep Gamma by her side by convincing her that everyone else hates her and thus removing all possibility of Gamma becoming friends with anyone else. This is due to Zimmy's own difficulty making friends.
She and Zimmy share an unexplained telepathic connection, and they communicate to each other solely through this way. As a result, she and Zimmy have developed an extremely close relationship, to the point where Annie has referred to the pair as an "item", something Tom has confirmed. Zimmy herself has said that she loves Gamma and wouldn't be alive it it weren't for her. However, Zimmy's love for Gamma has shown to be somewhat possessive, as seen when she translated what the students said to Gamma as insults and flew into a rage when the Antimony (as Zimmy) got too close to Gamma in Zimmyngham.  
- She is in no way connected to that girl from the photo.
- Gamma hails from Birmingham.
- Antimony knows a little Polish and thus can speak with her.