...child pulling a sled...
All I want to know is can I steal the sled like the mischievous thief I am and ride it down a large hill and off a cliff?
But seriously, I have no problem with people of all ages being in my games. It adds immersion. I'd rather not see them be immortal since I feel that only fuels the http://tvtropes.org/pmwiki/pmwiki.php/Main/LordBritishPostulate and rage if they're acting no good at all. I'm of the opinion that whatever someone does is their own business; I may not particularly care about said child (not unless I, as a person, or my characters themselves grow to), but I'm sure people don't go running around condoning various nefarious acts against them. If it happens, then it should happen for a reason, such as to demonstrate how immoral someone is, or how far they've slipped into instability.
And sometimes accidents happen, but children should be as safe as humanly possible, wherever they are. No parent who cares about the well-being of their child would allow otherwise, but there are tragedies in the world.
I'd like to see something done with them if possible. They're people and make decisions, if in different ways, and of course see the world differently. There wouldn't necessarily have to be quests, but interaction doesn't need to be limited to one choice on either spectrum.