WARNING SPOILERS FOR SEASON 2
Ok, so I had this theory for a while now and just didn't know where to post it. (Please excuse my grammar, English is not my first language)
So in the season one when Gabriel looked at Chat Noir's ring and looked at Adrien's ring think that he may have realized that Adrien was Chat Noir because in the season two episode "Despair Bear" the Hawk Moth has the chance to take Chat Noir's miraculous, yet he doesn't. Now I think that he doesn't do that in these later episodes because if he can take Ladybug's miraculous, than taking Chat Noir's would be easy since it belongs to his own son. Even if Hawkmoth takes Chat Noir's miraculous now he would have to deal with Ladybug still which I guess would be "the hard" part. At the same time I can see the point where if Chat Noir's miraculous was taken and he could no longer help Ladybug she would possibly have trouble too.
I feel like there are holes in my theory and I had thought of this theory back in April 2016, and I feel like I was able to add to my theory withe Despair Bear episode (then again it is a kids show, so i could looking into it too much).