Reasons to leave kudos (or likes or notes) and positive comments on fanfics.
My friend is crying over a long comment on her Viktuuri fanfic because the user wrote about how much they loved it.
She was smiling as she read it allowed to me.
She laid down on the floor and cried about it.
She was shocked by the number of users and guests gave her kudos.
Let the author of the fanfics you like know why you loved that work.
It goes a long way.