"You shouldn't have put Lily in Gryffindor." The boy was seething with anger over being separated from his friend and that made it difficult to get a clear read on him.
"I would not have sorted Lily Evans into Gryffindor if she had not belonged there." From what the Sorting Hat could make of the boy's mind, he very much wished that it had put Evans in Slytherin, in the House that he thought he was sure to be sorted into.
The Hat had no firm rules on placing friends together. It was hard on a child to be separated from their closest friends, but most children were capable of either make new friends or maintaining the friendship despite being in separate Houses. Severus Snape fell into the latter category, if the Sorting Hat was any judge.
It was glad of that, as much as a Hat could be glad. Most people at the school knew that the Founders had all been friends, but from time to time tensions sprang up between one House and another to the point where friendship between them was almost taboo and right now those tensions were between Gryffindor and Slytherin.
And Severus Snape was so very much like Salazar had been, when he was young and newly living in a strange country with unfamiliar customs and a language he could barely speak. Desperate to prove himself, carefully hiding his flaws behind a veneer of refinement that in time came to be considerably more than a veneer, and willing to do almost anything to get ahead.
He had mellowed out in time, and the Sorting Hat thought that Snape would too, no matter where the boy was sorted. But his love of learning was entirely in service to his ambition and that contraindicated Ravenclaw. The cunning streak that made him so suited to Slytherin also made him one of the very few people who absolutely could not be placed in Hufflpuff, even if he might have benefited from that House's egalitarianism.
"Are you going to Sort me, or are you only going to sit on my head?"
"I am sorting you," the Hat said. "It merely takes me a little time to work through all of your traits and determine which House would suit you best."
The boy did not voice the thought, but he was clearly pleased to be complicated enough to take some time to sort.
As a means of encouragement, the Hat began to list out what it had seen in the boy, "You're reasonably clever, meticulous when it suits you, more courage than you give yourself credit for–"
"You aren't going to put me in Gryffindor, are you?" the boy demanded. He sounded slightly horrified by the idea. It was a strange prejudice, considering that the boy had grown up surrounded by muggles and that he had no memory of his mother extolling the virtues of Slytherin House.
For half a moment the child's need to prove himself flared up, and the Hat realized that it was not a desire to prove himself to the world at large, but to a specific pair of people. To the grandparents who had disowned Eileen Prince for marrying a muggle. His mother had been in Slytherin, and so the boy hoped that his other relatives would take more kindly to Slytherin than a Gryffindor.
The Sorting Hat supposed they might, but that would have no bearing on the sorting itself. The Hat had been tasked with placing students where they belonged, not where their relatives wanted them.
The boy had courage. It had taken no small measure to befriend a muggle-born girl, while intending for the pair of them to be sorted into Slytherin. The Sorting Hat could see the childhood fantasies he had ruined by sorting Lily Evans into Gryffindor.
They would both be in Slytherin. Snape had cast himself into the role of Evans' protector. He would valiantly stand between her and any blood purists who insulted her, be her knight in shining armor. There was a dark side to this, or something that might turn dark given the right opportunity: he expected to be rewarded with her gratitude. It would be hard on him, especially his pride, if he was rebuffed or if he was the one of the pair who needed protection.
The boy's courage would falter, perhaps fail to fully develop at all. He would become bitter and resentful and turn inward on himself, eating his own strength until he had nothing left. His courage was still immature and selfish and needed some sort of validation.
He would grow out of it given time and opportunity. It was up to the Sorting Hat to place him where he would best have the opportunity.
Snape's seed of courage would be valued in Gryffindor in a way that it would not be in Slytherin, but Snape lacked a Gryffindor sense of daring. He would most likely never develop the flair for dramatics that Godric had so loved during his younger years and that Gyffindor as a whole had never entirely grown out of.
That would put him at a disadvantage. The older students, the ones who had reached the point where they understood the value of quieter kinds of courage, would not mind, but the younger ones, most especially the first years that this boy would be rooming and taking classes with, would push the boy into the kind of daredevil stunts that had always appealed to Godric and, so young as they were, not many of them yet had Godric's ability to look beyond a surly exterior.
Evans did, and she would happily help drill it into the rest of her classmates– if only Snape would allow it.
The Sorting Hat did not think he would. Their friendship would be able to bear Evans's independence, would likely be able to bear the children being separated into different houses, but it would not be able to bear Snape becoming dependent on Evans. The boy's pride would not allow it.
Severus Snape might very well turn out to be courageous, but he would not become brave in Gryffindor. He would be better suited by another House, and if there was some division between it and Gryffindor, that was all the better. Snape and Evans had the courage– and more importantly, the friendship– to cross the barrier between the two houses that were currently on the off and Hogwarts as a whole would benefit from that.
"You aren't going to put me in Gryffindor," the boy repeated with a firmness that belied the unasked question still roiling in his mind.
"No," the Sorting Hat said. "The place for you is in SLYTHERIN!"