just find a place to go around it or above him

it took me a while to figure it out. if you go past the first guard as hermione, look at
the very end of the aisle of books and you'll see a flat box on the floor. use hermione's
reparo charm to bring the box back and you'll be able to get on it and on top of the book
case. you can take all three characters over the bookcase and too the end. there are also
3 bottles of stamina juice on the top of the bookcase as well.

all i had to do was think. since it wasn't moving i kooked and saw the bottom of the box
and moved hermione there and did the reparo charm and the box became a box again and you
could go on top of the bookcase and get past the guard.

i did that bit all i did was think the guard is standin still so there is another way
across and if possible i always play as hermione so when i saw the box i just used reparo
but when i got over i nearly got caught by a prefect.