Maleficent appreciated the help that she needed from the twins, and she herself, has been seeing them as her own children. She promised Fili during the early part of the journey, that she would protect his younger brother whenever she could, and keep their family together. Now, she was already seeing them as her children, and they were already becoming attached to her, like children staying close to their parent. She grew fond of them, and that was when she realized that she had family. Managing to get into the cave, she winced as she was carefully placed back down onto the ground. She didn't have anything that would treat her injury, and she doubted that the company had anything to help her. All she could do now, was rest. 

"Get some sleep, we start at first light", she heard Thorin say, glad that he decided to let them have a break, and allow herself to heal. "We were to wait in the mountains until Gandalf joined us. That was the plan", Balin pointed out. "Plans change. Bofur, take the first watch", he told his comrade. 

A bedroll was all that Maleficent could lay on at the moment, and she let Fili and Kili stay with her, so she slept between them, only for the youngest to snuggle against her chest, like a young child needing warmth.