Lust
Salazar lazily gazed across the grounds of Hogwarts from the staffroom, observing small moments between the students. He watched a group of fifth year Gryffindors fall about laughing at something one of the boys had said. A group of Ravenclaws were chatting close by, less loudly and rambunctiously. He saw a couple of Slytherin boys, some sixth years he believed, tormenting a Hufflepuff boy. He smirked. He should probably stop it, but the boy was muggleborn, and in his mind, the fact that he couldn't defend himself was just proof that he did not belong.
None of them belonged in his mind.
His attention was caught by a young couple, a Slytherin boy with a younger Ravenclaw girl underneath a tree nearby. He watched as a comment from the girl, complete with a raised eyebrow, prompted a snort from her companion.
He was reminded, in short, of his own relationship with Rowena. One of mutual abuse that neither really meant, and a tendency to sit back and mock their other two best friends.
They were a force to be reckoned with when combined.
That was something Salazar was really beginning to notice.
He would be a fool to deny that he found her incredibly attractive. Not just physically, although that was certainly true. Many better men had fallen under the spell of Rowena Ravenclaw's dark eyes, her long flowing hair, and her slim yet still curved figure.
However, there were other aspects of her that were attractive to him. Her wit, her endless sarcasm, but above all, her detachment.
He knew that Rowena would understand that he did not want to have any form of clingy, joined-at-the-hip relationship.
Because he didn't. Right?
In his head, there was more to his musings than lust. Not love, but more, calculation.
He knew that he needed an heir. To complete his control over this school, he needed a way of carrying on his legacy. He needed a child who could pass on the skill of Parsletoungue, who could continue his work on his Chamber, which he was so close to finishing that he had begun his search for a Basilisk.
Who better to fulfil this ambition than Rowena? She was already a mother after all, and a very good one at that. He saw the love in her beautiful eyes when she looked at her child, now nearly fifteen.
And if Rowena could still love Helena that much, after everything that the girl was putting her through, he was sure she could love a child even if they began his dream of removing muggles from the school.
Right?
He was sure that what he felt was mostly lust towards her.
Because anything more would be too farfetched for the unfeeling Salazar. Wouldn't it?