A/N: And... we're taking a bit of turn from canon here, but (this is classed under "mystery", after all!) I'll let you guess at what exactly the meaning behind this is. Though I will note that nodding could be taken to be a grudging but benign form of acknowledgment *wink*.
It was Hogsmeade weekend, again, and he didn't like to see her with Potter, but despite the winter dragging on persistently and the two days that had been just a little warm, effecting a street full of muddy slush, things seemed to be looking up, just a little. The new cloak and robes from a mysterious benefactor somehow changed how people looked at him, especially Slughorn. They were new, brand-new (although they had been washed before being given to him), a luxury he'd never had before—could never afford before—and especially not out of a dense woolen, silken twill practically redolent of wealth. The cloak appeared on 9 January, wrapped in plain brown paper, but the robes had been left under the Slytherin common room tree on Christmas day, and he had been reluctant to wear them, except that he had been provided with four sets. The cloak was wool, a grey-on-black jacquard, and somehow Mother had managed to send a scarf in Slytherin colors. Today, as he had frequently, he wore them and it somehow meant that the other Slytherins avoided him. But it was, if he could manage to grasp at a completely foreign feeling, the avoidance of one who baffled them, befuddled them beyond reason by suddenly changing his footing in society, such that everyone else looked at him with newfound respect.
"Snivellus!" Black exclaimed, as Severus glanced in a store window.
"Leave him be, Sirius," Lupin scolded, and nodded at him as they walked past.
He was completely unaccustomed to being summonsed for the weekend, and he was further unaccustomed to then boarding a train and finding himself at some odd station, only to be met by a dark haired man in blue robes who studied him silently for a moment, then took his hand and apparated them both to the still frigid seashore. They were quite entirely alone.
"I take it you have adequate footwear?" the man inquired, raising an eyebrow.
"For what, sir?" he responded, "I hope this matter has nothing to do with the Dark Lord?"
The man looked quite confused for a moment, as if he didn't know what to say, but he handed Severus a parcel of wrinkled newsprint, inside which he found a new pair of dragonscale boots, felt lined, and for which he changed, childishly eager, the cracked leather oxfords on his feet.
"Eileen is recovering, though slowly," he said, as Severus fastened the second boot.
"Mum?" he asked, and mentally chastised the half-blood ignorant of propriety that he had been when he called her that.
"Yes, Severus, Eileen Teresa Prince," the man said, looking distantly out at the choppy foam.
He managed, if not smoothly, to inquire, "What about Father?"
"I don't know." And he repeated it. "I don't know what's become of him. And unfortunately my weekend is quite full of appointments and I have borrowed you only briefly. Come now."
He took Severus's hand as if coming to a decision, and apparated them to Hogsmeade.