Tell her she's your best little girl.
She brings him a picture almost every week. Tuesday pictures go to Lindsay, Thursday pictures get mailed to Granny and Gramps in Montana. Monday pictures go to Mac (which make most of the lab techs smile in addition to their fearless leader) and Wednesday pictures go to Miss Olivia the babysitter. But every Friday, when Danny sees his little princess after school, she leaps into his arms, waving a sheet of paper just for him.
She draws baseball diamonds one week and a lighthouse the next. She colors family portraits for them all, but his copies always have Lucy in Daddy's arms. On bad days—because he knows you can't love your father unconditionally every day—she'll draw him in a time out chair. This generally happens after he's only let her have one cookie behind Mama's back and not two or three.
But every time he gets that piece of paper with her marks on them, he says to her, "You are my best little girl."