Johnny did lean on Mary for support. It was twofold, really. He wanted to touch her and have her close, but he also needed to be helped. There was no way for him to deny it or play it off, either. He'd been dead. He'd been out of touch with the world. There wasn't really an argument that could be made. "Just a scratch" didn't even pretend to brush off what had happened.
He smiled a bit at Anna, not sure if she was still on his side of things, despite the fact that he was sure that Castiel had likely told her long ago what he was. Hearing and seeing were two different things, after all.
"Violent fish?" Johnny looked at Mary as they exited the camp area. "Like piranha?"