Terms of endearment honestly freak Severus out a little bit? He was never exposed to the traditional kinds most people have heard growing up ( sweetheart, darling, honey, dear, etc. ) His parents loved one another – toxic though their relationship may have been – but it wasn’t the kind of domestic that warranted these terms. Eileen tended to give nicknames by means of Gaelic terms for animals – Severus was Raven, to match his father’s Hawk – but that was about the extent of it?
In school he obtained nicknames of a viler sort, though his Slytherin friends did utilize Twitch fondly, it’s hardly endearing. When he first started hearing things like this he was – well for lack of a better description? He was this emoji:
100%
He finds them strange and in all the time I have written him, Severus has only used terms of endearment like this in heavily divergent verses ( such as his Prostitute AU ) or in tales where he has become a parent himself and even then, the endearments tend to be toward the child rather than a partner should he have one, which he rarely does as I’ve only ever dealt with him adopting tbh.