Marion looked excited heading to the hospital to meet Shana. She is disappointed with Gabriella's decision not to let Shana go out and return to her home. There are several plausible reasons, but still unacceptable to Marion, as Shana's best friend.
Now Marion has to come and see the condition of some of the patients who are suffering from rare diseases, and some even experience things like Shana.
However, if Shana can recover from sucking Marion's blood, why didn't Gabriella take Marion's blood to serve as a serum for the recovery of many people who had turned into ferals?
What is the consideration of the woman to the point of not doing a profitable option.
Marion wouldn't refuse even if Gabriella really wanted Marion's blood. But it seems, it has to do with the last sentence spoken by Gabriella, that if many knew that Marion's blood could be a healer for the ferals, it meant that she was in danger.