Castiel allowed Meg to lead him through, to place his arm around her waist, because he wasn't making these movements otherwise without her permission. He supported the weight of her body against his, holding her firmly in place, so she knew she could lean on him without worry. He was there. He had her. Aside from when he comforted her in the wake of her nightmare that evening she fell asleep in his apartment, when her power kept sapping into him, this was the first time after she'd been rescued from Crowley and his men that he was able to offer her some sense of comfort. While he didn't voice it, he was glad he wasn't doctoring any wounds, because he'd been genuinely worried that Meg would have found herself in some sort of trouble while she'd been away for the past week.
"Alright then, I will allow you your rest." He took her at her word that all she needed was rest because he wasn't sure how to deal with a drunk demon. It was a new experience for him and he'd look to her with guidance, while still attempting to be as helpful as he could without asking for her input. He didn't even think about her jacket and boots left in the distance behind them, but he'd been so focused on getting her back to his apartment, so she could shower and rest and he'd know she was there and hopefully, she wouldn't be running off in the morning as well.
A flicker of confusion played across his features when she asked her question, since he wasn't certain what she was talking about. She came back. She was allowing him in once more and he considered that to be a good thing. While it didn't erase the past week and more he hadn't seen her, he could look past that.
"I don't understand, what do you think you messed up?"