"Well, let me start with the first and last questions," Severus said, "since they're the easiest to answer: yes, to both." He paused for a second to smirk whilst thinking of the best way to tackle the middle question. "My mother's maiden name was Prince -- that's the simplest answer, but there is more to it. Are you up for a small lesson in Welsh language and history?" he asked, raising an eyebrow. But the question had been largely rhetorical, on his part. He only paused for effect and didn't wait for Sappho to nod or answer before he continued.
"There are two words in Welsh that can be used to mean prince: 'pendefig' and 'tywysog.' 'Pendefig' has multiple meanings and is often used to refer to any peer or nobleman. 'Tywysog,' by contrast, only means 'prince,' but ironically that alone does not always imply someone called 'Tywysog' is of noble birth. Oftentimes commoners -- usually wealthy merchants, but not always -- were referred to with 'Prince' as a surname because they had done some sort of favour for the reigning king.
"One side of my mother's family took the name Tywysog and Anglicanised it to 'Prince' at some point, but they may or may not have been nobles in their own right. If they weren't, I imagine the king in question was also English. Hense, calling themselves 'Prince' instead of 'Tywysog.' The other side -- the Wynn side -- were pendefigion, demonstrably of noble birth, if not princes, as such. These days, however, they are impoverished nobility. It's the worst of both worlds, really -- all of the arrogance, but with none of the gold."
Severus frowned when he'd finished. He'd said the last bit without thinking, having been caught up in the tale of his family history, but he couldn't helping wondering now if Sappho would view him differently. Well, she had moved closer after he said he was half a prince. Did that mean she had, in fact, been slumming before and now she considered him truly worthy of her? He wasn't certain if that would bother him or not, actually. Best to see how she reacted first before he decided how to react to her reaction.