That was not all.
Su Er tested it and found that he could not touch Hermione at all. It was as though a membrane kept him outside; he could see Hermione, but could not make contact.
Su Er also tried to see whether he could leave the Library, but the result was just as he had expected.
"Looks like I'm trapped here too." Su Er gave a bitter laugh and looked at Hermione a short distance away. "How am I supposed to break out of here?"
"Professor Dumbledore never mentioned anything like this."
"Perhaps destructive magic..." Su Er thought of a method, then put it into practice.
The shelves in the Library looked as though a gale had swept through them. The wooden frames shattered, and the books on them tumbled to the floor, including those on the shelf in front of Hermione.
Clearly, destructive spells had not achieved the effect Su Er had hoped for at all.
"Sectumsempra!" Finally, Su Er flicked his wand irritably, sending out a blade of air, but the magic was swallowed completely by the darkness. Only when a slicing sound came from far away was there any sign of it; some unfortunate book had taken the hit.
Since it was all futile, Su Er was certainly not going to keep foolishly wasting his magic. He put away his wand and sank into thought, considering how to break the impasse.
None of this affected Hermione at all. The spaces the two occupied were like two separate soap bubbles, unless Su Er could find a way to make the bubbles intersect, then merge or even burst.
Or perhaps, if time passed inside Hermione's bubble like sand through an hourglass, then once it ran out, an invisible pair of hands would turn it over and start again.