Just so we're all clear on what we're talking about, this is a Hob:
(http://fc09.deviantart.net/fs71/f/2013/007/7/e/hob_by_johntfs-d5qqm68.jpg)
Take that in for a second. Then remember that in order to have a "Hob changeling" some human person had to have sex with that thing. I'm not saying don't do it. I'm just saying that if you do do it, the changeling should have some really interesting, really unpleasant aspects on his sheet like Daddy's In a Rubber Room. I Ate My Mommy at Birth. Something like that.