Clearly this is all the more reason that she must know him because if there's one thing she seems to be good at, it's befriending the not-so-social. And she collects Spades, apparently. I don't know why she does but she does.

Though Nico has been by, I expect. He tends to bounce between dressing like a penniless artist - though never outside of the Castle - and, well... a Nine. The Nine wear, of course, needs to be immaculate so it's entirely plausible that he's found his way to Charlie's at some point. He'd have been cordial but not especially warm - it's nothing personal, he just apparently isn't always so good with people - but I'm sure there's potential for something there. We shall see what develops?