[1/3] Dinah's probably majoring in something so she can help out kids like her - social work or criminology or human services or something of the like. That's how Cass is involved - she's assigned to Dinah through some sort of Big Brother/Big Sister type program Dinah's involved with on campus.
[2/3] Helena's only really going to school because you're supposed to, she could not work for the rest of her life, but she's probably doing something like mechanical engineering - something that she can use her hands and do physical work, but it also requires attention to detail and precision.
[3/3] Dinah works her way through school, waitressing (and later bartending) at one of the campus pubs. Helena always comes in and sits at the end of the bar, eats and drinks alone without talking to anyone, but one night Dinah sees her working on some sketch for a design for a final project and starts up a convo with her.
Shit. Yes to everything! I’ll even put this in the tag.
So Dinah is not exactly anti-social, she has a few friends, she’s just very selective, and very tired sometimes. She has a low tolerance for most people’s bullshit.
And Helena is even worse in the isolation department, and her public perception isn’t helping: she is assumed to be a rich snob who thinks she’s above everyone else and doesn’t speak to the common folk -- and Dinah can sense that’s not really true. She has that special skill to read people (blame it on her area of interest), and she is not really sure Helena is the girl everyone says she is.
It’s made clear, when their first ever conversation basically consists of Helena misunderstanding her sarcasm, missing cultural references and overall just looking very confused, while leaving a stupidly high tip to Dinah (she’s unaware that it is stupidly high, of course.)