Thestrals
(Sorry if I spelled thestrals wrong.)
Cleve flew through the forest with Eva. Actually, Eva wasn't doing much in the way of flapping, but as long as she kept her wings open she was easy to pull.
Cleve came into a clearing in the forest, and stopped flying. Eva blinked. "Huh? Are we safe?"
Cleve looked at the creatures in front of him. They looked a little like horses with wings, except very dead like. "I don't know." He replied honestly. He let go of Eva, she was staying up on her own. "Excuse me," he called out to the creatures. A few of them turned to him. "Not to sound rude, but could you tell me what you are?"
"What's what?" Eva asked. "I don't see anyone."
One of the creatures walked up to him. "We're called thesterals."
"And Eva, why can't she see you?"
"What can't I see?" Eva asked.
"We can only be seen if you've seen someone die."
"Oh." Cleve swallowed, remembering his brother.
"Da? What is it? You're scaring me."
Cleve sighed. "We have to go." He told the thestral. He flew to Eva and as they flew away he explained what he had seen.