Adrien is not the best at context clues, but he's guessing Spark is the same guy as a cat. So his father didn't know about him, or that he could turn into a guy who looks like Adrien, or that he's also a talking cat... It's a good thing he is good at keeping identities straight or this would be getting too confusing.

"Uh, alright... I guess I can talk to Leia." Whoever that is. "And I won't tell Father about you - if he ever shows up."

Which he has a feeling he won't; he doesn't know why his father would be getting mixed up in magic stuff in the first place.