It didn't seem like much, but at least Ron was capable of what she was asking. As much as he'd prefer to be able to fix everything so she didn't have to be scared, he knew he couldn't. Even if she'd been frightened by a flesh-and-blood person or creature, Ron wasn't an Auror, he wasn't a hero, he just... looked after trees. He kept one hand over his heart while he wound the other around her waist and let her tuck her head into his shoulder. "You're not dead." There was no way Ron would be this calm if Lavender was dead, but he couldn't think of a way to say that.
He tightened his arm around her when she asked him not to let her go. He'd never wanted to let her go. Even now, he knew this was temporary. Getting to hold her again. She wouldn't let him do this as her friend if she weren't so terrified, and Ron was determined not to give her a reason to regret it. Even when she moved against him and her shirt rode up in the back, Ron just smoothed it down and held it there. "What time did you wake up?" he asked. He wasn't going to suggest she sleep again, but if she wanted to he could wait with her.
"I'm here." Of all the people in the world to make Lavender feel safe, Ron honestly couldn't understand why it would be him. Ginny and Parvati had got better results in the Defence Against the Dark Arts. All Ron could remember was that inferi couldn't feel pain so you were supposed to fight them with fire, like that plant that hated the light. "I'll stay as long as you want me to, Lav. Until you kick me out and tell me to go home."