Derek nodded and gave her a small smile. "Thanks," he said. He would've felt worse tracking mud through her house in addition to dripping all over the place, so he was glad that she agreed to go get the bag and bring it to him. She was already understandably and justifiably upset with him, he didn't need to add another reason to her list. The look on her face just before she turned to head up the stairs broke his heart. She was afraid he was going to leave...he could see it in her eyes.
So when she disappeared up the stairs, he stood still, waiting for her to return and he took the bag from her, eyes following her gesture to the bathroom. Derek nodded with a little smile. The more she talked, though, the bigger his smile became. He didn't know why it was endearing when Patty rambled the way she did when she was nervous or frantic — it drove him absolutely apeshit angry when Stiles did the same thing — but it was. "That sounds good, thank you," he replied, giving her a fond look before he finally started toward the bathroom to change.
All that was in the gym bag was a white tank top and a pair of black basketball shorts with legs that hung around the top of his knees, but they were dry, so that was good enough. It would've been better if he'd had a spare pair of boxer shorts in there, but he didn't, so he just went commando under the shorts, figuring their legs were long enough to keep it from being too much of a problem.
Once he emerged, he had the gym bag hanging loosely by its strap over one shoulder and a pile of wet clothes in one hand with his soaked sneakers in the other. "Yeah, much better. ...can I still dry these? Is that cool?"