Remus felt his own lips turn up into a smile at the sight of his son's toothy grin.
"Mum's right. You're certainly not in trouble. Now, remember last week when you came into mum and dad's room when I was sleeping? And I was hurt pretty bad, right?"
"Uh-huh," Gabe said, looking slightly confused.
"When your daddy was very little, as young as you in fact, he had an accident. He met a werewolf who wasn't being safe on the full moon and he got bitten. Right here."
Remus pulled back the collar on his shirt to show a puckered white scar on the back of his left shoulder.
"And because that happened, Daddy's a werewolf too. That's why he has to go away one a month, because he has to change. But you don't have to be scared, okay? I'm always safe and then I can come home to you and mummy. Right?"
Gabe reached a small hand up and touched the scar on his father's back gently. He was silent for a minute, which felt like an eternity to Remus, and then asked.
"So you can change into a wolf?"
Remus nodded slowly.
"Cool!" Gabe said, leaping off his father's lap and running to his room. Remus exchanged a puzzled look with Tonks. The boy returned, clutching one of his stuffed wolf toys. "Like this?"
"Sort of," Remus said, laughing a little. "I go away and turn into a wolf, and I sleep like that for the night, and then I come home to you."