Given how Vanitas was raised, he has a rather intriguing
set of manners and behaviors. These range from short,
formal bows (mainly used in introductions) to one that means
wholehearted trust and respect. The second being one that he
would only use toward someone he is in a relationship with and
feels this way towards. His mannerisms tend to seem sloppy,
but he tries his best not to use his princely title to his advantage.
He has run from it, he doesn't wish to embrace it. However, that
doesn't mean that he will ever stop using his manners unless
he feels threatened. If he ever feels threatened or feels
someone is threatening his family, he will go on the defensive
and be sure that the threat is either warned or neutralized.
His family is the most important part of life for him, if someone
were to threaten that, he would be sure to get in the way at
the cost of his own life. His mother taught him the importance
of family and to always value and protect them. It's part of what
makes him question if his father was really trying to kill her
or was coming after him the night his mother was supposedly
killed.
He has a hard time with trying to stay in one place, making
it hard for him when he's injured and having to stay in bed or
remain in one spot for elongated periods of time. It also
causes personal side effects (I will not name them since he's
rarely injured bad enough for him to be bed ridden) that can
lead to him being restless or even fidgety.
"Signora" is usually used as a substitute for "Mrs" or "Miss".
It's mostly how he shows respect for an individual, showing
them the most respect he can when speaking to strangers
and friends alike. In the same way, "Signore" is used the same
way for males.
He has a few animalistic tendencies and behaviors, those
of which can be sown in sounds or simple animal like
movements. A growl showing anger or a protective mood just
as a purr can mean happiness or simple relaxation around
someone. A rumble is contentment or love, though unless
he truly feels this way about someone, he will neither purr nor
make a rumble noise. There is another noise he makes when
aroused, which is very highly similar to the sound of a purr. This
noise is made with his teeth pressed together and exposed,
unlike that of a regular purr.