"Grandfather." Anna sweetly called out her grandfather, who is currently reading a book on the sofa.
Marcus looked up to Anna and suspiciously stare at her. Anna has never called out to him in a sweet tone of voice ever since he announced to her that she is to wed Juan. For his granddaughter to call out for him like that must mean that she needed something from him.
"What is it that you want, Anna?" Marcus dotes on his granddaughter, but his way of doting her is what you call tough. If he isn't tough on her, she might turn out to be unable to fight back for herself, and other people will take advantage of that.
"Grandfather, just because I'm calling you out that doesn't mean that I need something." Though Anna indeed needs something from her grandfather, she is not going to tell her grandfather that.
"Don't think that you can fool me," Marcus said in a stern tone of voice.