Who's Gabriel doesn't seem such a big mystery to me, since everything is explained at the beginning of this episode. Marisol and Gabriel grew up together and they both belong to criminal families. So what's the mystery?
Now Gabriel is the big psycho boss of the gang and blackmailing people to do what he wants, although to me it's not clear why Marisol is running for mayor, just to be a puppet in Gabriel's hands. Would you accept to have all your life manoeuvred by some criminal?
What is even more muddled is the Julio plot. Why is it so important that Julio is incriminated for a rather irrelevant double murder? Nobody explained that, yet. More explanation maybe is to follow, but so far the Julio plot is completely nonsensical.
Also, a lot of romance going on, between mega creep Tom and Brittany (quite disturbing), Patty and Jeff (kind of the only real romance) and Billy and Marisol and she's such an hypocrite and liar to make it almost revolting to watch.