Arthur was pretty aware that he had a kid, but he never bothered too much about about it. I mean is not like he didn't care a lot but not too much either.

For his defense he thought you would be just fine with your ma, he never suspected as everytime he visited you and your mom you were fine.

Or maybe he wanted to convinced himself of that, however after he showed up for suprise, he witnessed one of your mother's beatings.

He couldn't help but to protect you and get you away of that horrible woman who calls herslef a "mother".

He knows he can't give you the best of the lives but better than living with that woman. "Hey, got'cha some food" He said handing you the plate as you were sitting on a log in the camp.