He/She will be protective.
Would love to provide perfect guidelines for every walk of life even if you don't ask.
Even if she herself fails to practice those guidelines, she'll always press you to do it to prove that her guideline are actually perfect.
Parents give most of the responsibilities to the elder one, so you can have much time of your own.
Did something wrong in team? Don't worry. She's the one to be grilled by the parents for most of the time.
If she is good in academics, computers etc then she has to help you out. Even parents would persuade her to do so.