Rose and Ron!
Ron didn't much care about the demons that everyone else appeared to be battling off. The way it looked to him, most everyone had the situation under control. He'd cast a hex or two here and there, but Ron only played his part until he had the opportunity to break away from the group and go searching on his own. Likely the stupidest plan he could have ever had, but could one blame him? His future daughter was out there. Trapped and hurting; possibly even dead. If anyone actually expected for Ron to keep the order and stay with everyone else, they had another thing coming to them. He was stubborn, he was impatient, and he was downright terrified. Ron was also a Weasley. They didn't stand around and let people get in their way. They fought for their family, no matter how dangerous and impossible the chances of survival were. It was also probably why he was a Gryffindor. Bravery and all, even if it was foolishly used.
Once Ron got a good idea of where the others were being trapped, he tore his way through the building. It took some digging around, the help of some of the others included of course, but Ron eventually reached a door that hadn't been torn through as of yet. Spotting a demon guarding the area outside, Ron pulled up his bottle of holy water and hurled some of the liquid into the face of the creature in his way. It howled in agony, clutching at it's face as it tried to ease the pain Ron had caused it.
Ron certainly was no genius with the exorcisms. He had a quarter of the incantation memorized at best, which was why Ron chose to drive the demon back as best as he could before ducking in the room that he'd been aiming for. Before the demon had a chance at joining Ron inside, he dropped the small container of rock salt that he'd been carrying with him and began to pour it along the doorway to contain himself safely inside. Except...as he turned, he realized that he wasn't safely inside.
Another demon had been standing guard. And behind him, lay an almost unrecognizable form. Almost.
"Rose!" Ron darted for her, only finding himself cut off by the demon within a matter of seconds. Furrowing his brow, Ron took a step back and raised his wand. Several stunning spells were fired, but they weren't enough to keep the demon completely at bay. No, Ron had to do more than that. He dropped down, pulled out a crumpled sheet of paper from his pocket, and began to read from it as quickly as he could. "Exorcizamus te, om...omnis immundus spiritus, omnis satanica potestas...."