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There is very little in the anime or the manga on Atom's relationship with his creator after he is initially abandoned and left in the care of Ochanomizu. The 1963 and 1980 anime's as well as the manga treat the story of his creation slightly differently, and in the manga there are two different versions (at least two, with the "once upon a time" arc being different because Hoshie is in it).

I think the Herald Brothers episode may be the only one that has Tenma in it after Atom's creation (well other than the 'metal men' story which is an AU anyway). From the little bits that I could make out I think Atom referred to Tenma as "Tenma Hakase", calling him by his title, and not 'father' or 'creator' (unless I missed that). So at this point, their relationship is rather cold.

I do like how in the last few episodes of the 2003 anime, they do focus on the relationship between Atom and Tenma. It made their relationship between each other seem a little more fleshed out.

Tenma's role in the 2003 anime I feel was really more emphasized than in the 1980s anime (can't vouch for the 1960s anime since I haven't seen much of it). It's a shame that he doesn't appear more than he does in the 1980s anime. Heck, he isn't even present in Little Astro Boy (though I feel they did that to keep the lighter tone to that series). Hopefully he has a prominent role in the upcoming Astro Boy Reboot series.

Tenma's not my favorite character, but even I found it lazy that he just kind of disappears from the series in the other animes. It left out a lot of potential development.

Even though it might seem odd, Tenma is one of my favorite characters in the series. I think he's an extremely complex character and he needed more show time in the 1960's series and the 1980's series. The 2003 episodes couldn't have made me happier, due to his role throughout ALL 50 episodes.
I hope in the upcoming Reboot series they get even deeper into their relationship. I truly think that he is what makes the show.