Could it be as simple as House Elves do not use spells, instead 'willing' something to happen. Their abudance of magic does the trick... if Dobby wants to be at the Dursleys, boop, he's there. Then, House Elves by nature are not able/nor do they want to injure humans. Thus, the only way he can do damage to another human is by defending someone he is loyal to.

I also think this applies to free elves as well.

 

And what's up with cliche phrases like the one you mentioned or the "Harry has a 'people saving thing'! ". I've seen them so many times in fanfiction, that I'm wondering where people's imagination has run off to.

I also just love the all new and extended version of the tags for this thread!

 

It'd be boring and shit, worthy of a 500 word one-shot and that's about it.

That's why we don't do it.

Once again, the mighty Shezza has solved yet another conundrum.

 

Perhaps elves magic would kill them if they kill a human?

Dobby is just flat out the Harry Potter of elves. Rules do not apply?

 

Stupid thread, stupid thread, why won't YOU DIE???