He looked like the guy having an allergic reaction to peanuts in the video Ryan watched and Marquis called him "dad" in that video. So, I think it's safe to say that was Marquis' dad. I don't know why she folded the picture. Maybe seeing his picture is a trigger for Marquis?
It looks like Marquis is going to be the new Joker. It's an interesting blend of Bruce and Kate's archnemeses. Bruce's is the Joker and Kate's is her sister. Ryan's will be her brother or half-brother who is the new Joker.
In the third episode, Marquis said Ryan is a year younger than him and that Jada was away for nine months. Marquis would've been three months old when she left. Not to mention the Joker is apparently responsible for Marquis. So, the question of why Jada went away for nine months and erased her connection to Ryan remains.