"I must compliment you on your choice of mask, madam," a warm baritone said from roughly the level of Renée's elbow as she ascended the steps.  A black-furred feline sat statuesque upon the banister with his luxurious tail curled around his paws.  "Not a standard choice, yet not as uncommon as some I've seen.  I noticed one man with the visage of an elephant.  A singular choice, to be sure, bold and a bit exotic, but overall I think the decision an unfortunate one.  It did not flatter him.  Quite the opposite in your case, I assure you."  He blinked yellowy eyes -- no wait, were they green? -- up at her as he rose to his paws, extending his claws in a graceful stretch that just avoided leaving marks in the wood's finish.

"And if it is not too bold of me, perhaps you would permit me to accompany you for at least a little while.  I assure you, I will not muss your garments nor leave fur upon them, I promise you."  His whiskers angled gently upwards with the question, ears turning forward in anticipation of her response.  If she aquiesced, a smooth leap brought him to her shoulder where he artfully draped himself like a warm, velvety shawl, face on one side and tail at the other.

In truth, Schrödinger had little need of assistance to find welcome.  The Duchess had not been invited, but that hardly stopped him.  Servant entrances made gaining access to many places a trifle, but in this case he's used the attention paid to the arriving guests to slip inside unseen -- and no one would eject a cat from this sort of thing.  Cats were the secret-keepers of London; he'd glimpsed a few of his brethren padding silently through the noise, and what they overheard would bring status to some and scandal to others.

"I won't ask your name given the circumstances, dear lady, but I should like to know what you wish to be called for the evening.  As for myself, I believe 'Ro' shall do nicely."