This girl makes me uneasy...?

How is she with other people? Is it defo just you she's icy with? g nice to you? Could she like one of the people who is beinI agree with the person who said to be nice to her - it'll put her at ease if she really is feeling outshone by you. Either way, befriend her if you can; it makes life so much easier and you're bound to find out what the reason was that way (may take few months but chances are by then you won't care)