Pros and cons of Leo knowing Stargirl

In the novel Stargirl, we could argue that Leo is either better or worse off knowing Stargirl. In my opinion Leo is much happier off with Stargirl, she has taught him how to be more assertive, she taught him to be less timid, and at last she helped him be himself. However sometimes they seem like they were never meant to be, I mean Stargirl is an extrovert, she loves to talk and do things for others even if they would not consider doing it back. While Leo is an introvert and cannot live without someone else's opinion whether if it is his daily life or even future! Let us look at what might benefit Leo from knowing Stargirl and what might not.