whisper

to murmur

Don't you know it's rude to whisper?

She leaned over and whispered something in his ear.

He whispered to me that he was afraid.

behave

to act; to do things in a particular way

The doctor behaved very unprofessionally.

They behaved very badly towards their guests.

He behaved like a true gentleman.

She behaved with great dignity.

loyal (to somebody/something)

true; remaining faithful to somebody/something and supporting them or it

a loyal friend/supporter

She has always remained loyal to her political principles.