This is something that you'd have to fill out yourself. This is because the question is personally based on your preferences. Ask yourself which type of science topics you like. Is it Chemistry? Biology? Astronomy? Once you pick a topic, you can narrow things down.
For instance, if you pick Astronomy, then you can go for a sub-topic such as how supernovas happen or how stars form. This is of course an example and it may not be something you're into. So you'll have to determine which is your favorite.
As for how to tie it to your personality, that's also something that would be unique to you on an individual basis. There's not much I can do to help here. Ask friends and family how they see your personality, and ask yourself that same question. Then try to see how it could be found in one of the sciences.
Sorry I'm not much help here.
