If my brother is executor of my dads will, and he hates me what can he do to me regarding the finances?

We have never gotten along, my mother just passed away in April my heart is broken my Dad is 90 and I have been taking care of him. I am worried my brother will try and do something to me as the executor of this will which while not extremely substantial, has property and about 100K. What can he do to me when my Dad dies and won't be here to protect me from his greed.?