Voldemort saw that Nagini was asleep in the common room once again. He wondered whether she ever entered her dorm except to change anymore. It was now hard to believe what kind of magic she was capable of when she was asleep, her head tilted to the side and mouth half open.
He could take her out of his group, but that meant showing weakness to his once faithful Death Eaters and she would become a true opposing force. He could still keep contact with her, but she would most likely start to feel very wary of him afterwards. Her attitude with her other peers definitely meant something. He had a feeling that she could make her own rebel army sooner or later. Her potential was obvious, he couldn't risk it.
He could also prove his power by getting her out of his way. He was sure he could make her fear him. He knew she was much weaker and most likely wouldn't fight back unless she was truly angry. This notion was still with its flaws, he knew that for now, she was more powerful than he, simply because of how much more freedom she had because she wasn't restrained by words and spells.
Voldemort knew what he should do, to simply exercise control over her, to show them how he could easily manipulate her to do his will.
He failed to understand what could happen, with or without his interference. Although for now, she only considered him a friend, but it wouldn't be long before he found things take an interesting turn.