Nyon is a catman of Russian origin and lives directly under Luther's rule. Because of being directly connected to Luther for so long (and wide), his revival speed is extremely fast. To compare to Randal's even, where if he isn't in his coffin could take a very long duration to recover his form (even then not everything might come back at once), it is impressive in a way.One of the few members of the main house who is on the low spectrum for danger potential.
He would most likely try to avoid other humans and non-humans instead of directly confronting them altogether due to being more soft-spoken and shy.Despite that, and despite appearing quite timid and uneasy of things usually, he would do anything for his master.

Despite showing up often, Nyon only says a few things here and there aside from the given cat noises and laughs. He may also speak Russian! Just do what you feel would be cool and would make him stand out.

Line References

1, 2