Hopkins wouldn't go after someone who was popular within the house, because she knows that would make her unpopular. Maybe she'd go after Tiffany, but I think they'd get on well considering Tiffany is friends with Gemma. She'd probably go after John, but only once everyone else had turned on him, much like how she didn't go after Perez when he was shouting in her face on week 1, but instead later on when he had ruined his ties with everyone else in the house.
Even if she slags of Gemma on twitter it doesn't mean she wouldn't be pals with her in the house, because after all she is not friends with people because she likes them, but because they are convenient for her. A true gameplayer.