Eve did not belong to the Devil at the beginning How did she end up with him? God made her eat? Or, the Devil is greater than God, and he made her eat? Or, she chose to eat?
Which is it?
Her sin separate her from God. The devil just happens to be on that side.
As for your second question, God didn't make Eve eat any more than Eve freely chose to eat. The devil tricked her into disobedience. At least that is what the scriptures tell us.