The 49-year-old, who plays Billy Mitchell in the BBC soap, said that the newcomer's "cheeky" personality put him in mind of departed cast member Lacey Turner (Stacey Slater).
"She can be a cheeky little so-and-so, can Dan," he told Inside Soap. "One of the cameramen was talking to me about my role in [1986 film] Mona Lisa the other day, and Danielle piped up, 'Was that in black and white?'
"The way she's come on since her first day has been amazing. Danielle reminds me a lot of Lacey (Turner) - she's such a cracking little actress."
Fenwick also teased more details about his on-screen granddaughter's current pregnancy storyline, saying: "A baby story can go one of about 20 ways, so who knows what'll happen. But Billy will be by Lola's side."
Harold herself has admitted to being influenced by Turner, describing the 23-year-old as an "incredible actress".
Watch Danielle Harold chat about EastEnders and Lola Pearce below: