Her character was just super "wow"
What I loved about Marina was how unafraid she was of doing her own thing and going against what her friends and family told her to do. She's probably the only character on the show to be so independent and strong-willed. She was also very nice to the poor students.
She sometimes became the "poor little rich girl" archetype-- hella angsty. She's also such a user-- both in the sense that she uses people (like her old BFF Carla, and even poor Samuel) for her own gain. Also, she uses drugs. A lot. Messy af, and it sometimes made her frustrating to watch. I was super angry that she didn't tell Nano she was HIV positive before sleeping with him-- like, what the Hell?
Overall, though, I think she was pretty interesting, but it seemed like she was super angsty for no reason and completely overreacted to certain things. When she died, I was sad, but out of everyone on the show, she was getting to be the most frustrating to watch...
...not saying I'm happy she died at all! It was so sad and unnecessary, but plot-wise, it made sense. Her life was a literal soap opera.