kylo4
Cadet
I think this because Sloane says that Sydney is like a daughter to him and maybe Jack doesn't know it. Also, my mom gave me this kind of lame idea. It's possible that they will end the season with Sydney tied up going brother/sister. Or Sloane had a kid with Derevko and that's why they're so close to each other. There could be a million possibilities but I'm just throwing around strange ideas.