So I thought of this the other day, don't know if it's been done or not but oh well~~

So you know how Alfred went to live with Arthur when he was little?

Well my theory is that Allen did not go live with Oliver like Alfred did with Arthur. At least, not at first.

He ran away from Oliver and stayed with Native America (in his case Native America's 2p) for a good long while before Oliver managed to find him and take (drag) him back to his house.

Once there Allen refused to learn English for the longest time (though eventually did) and was mean and rude just to be spiteful.

(((He missed Native America)))

Though eventually (after a long while) Oliver managed to calm him down, teach him English, and other such things.

And so on and so forth history is known from here...

[Aka I'm too lazy to type everything out so yeah....]