Summary:
Madison is blunt and honest, not quite a tsundere but terrible at softening her many, many edges. She used to be terminally ill and resorted to vampirism to live a normal life a little over a year ago. Fantastical backstory aside, she’s still a normal college student with with high standards and aspirations, even if she does need to be knocked down a peg or three.

More Elaborately:

Madison is a formerly terminally ill kid and recently turned vampire with a catch: she has to kill someone, all on her own, and without any other vampire knowing within the next two years from her turning (so starting June 2018.)
 This is because, while she had to be a fit for vampirism no matter what to be allowed it at all, there’s still the fact that her parents are also both vampires and thus gave her an easy in to vampirism, and the demons don’t want to let the acknowledgment of nepotism go to waste. She has to be tested like just the rest.
There is, of course, the possibility that she doesn’t actually have to follow through with her end of the deal. There’s nothing stopping her from living the fuck out of the next two years now that she’s no longer frequently bedridden and low on stamina and simply just cashing in her metaphorical check when the reaper comes knocking. It’s one she considers out of obligatory contrarianism more than a few times, and more than once out of her own set of values. She doesn’t have the stomach for killing right now. The demons probably knew that, too.
Some whisper that it was the demons themselves who sabotaged the child with her first place in the first place, after all. Both parents had already sold their soul and asked for more on top of that, after all, so Madison would just be playing into their hand perfectly, and wouldn’t that just be annoying?
More importantly, though, is that Madison has time and a five year plan and beyond for a life that she’s determined to live as close to her real values as she can. She wants to be a doctor, as inspired by Bernard, who’s practically family. She wants to run a 5kilo and join a sorority and do everything that every hopeful college kid dreams of. She’s just a normal kid who’s a little too smart for her own good and way, way too spoiled even for all the hard work she does elbow in.
She’s more than just the guillotine hanging over her head or the risk she has to others, the circumstances that got her this far. There wasn’t any point in her becoming a vampire if it wasn’t to actually go and live, and, hell, even the demons agreed as the clock ticks away.
At least this way she can make an informed decision before it’s too late.