Mac Dictionary’s definition:
experienced in the imagination through the feelings or actions of another person : I could glean vicarious pleasure from the struggles of my imaginary film friends.
• acting or done for another : a vicarious atonement.
• Physiology of or pertaining to the performance by one organ of the functions normally discharged by another.
ORIGIN mid 17th cent.: from Latin vicarius ‘substitute’ (see vicar ) + -ous.
I know the vicarious feelings of my novel characters.