To which series do these questions refer?
1. Does Astroboy realize that he's just a replacement for Toby?
If you refer to the 80s series, I would say, I do not know. Papa-san rejects him because he is error-prone, yelling that he is only a robot, and perhaps even that he is not his son, but I cannot recall any reference to Tobio after Atom's creation.
For the newest series, definitely yes. Although I could not understand the dialogue, I viewed episodes 5-7. It was clear that Tenma had programmed the robot with his deceased son's 'memories'. Example, as Atom and Elefun are participating in a three-legged race, Atom has flasbacks, memories that Tenma put in him, so he would, rather than being a replacement for the dead boy, be a ressurection of him. Several other occurences of these 'memories' happen, and Atom Asks Dr. Elefun, "Who is Tobio?" If you view the trailer, you will see Atom in Tobio's room, looking at a photo of Tobio. Moreover, in the episodes I just mentioned, Atom looks at his own reflection in a window, and 'sees' Tobio.
2. If so, does the thought bother him at all?
Pertaining to the current version, definitely yes. Atom is very troubled about this fact. The series opens with Elefun awakening Atom, and apparently he had tried to expunge all his memories before this event. He addresses him as 'Tob...', looks at the project's name, which conveniently has the acronym 'ATOM', and names him this, instead of 'Tobio'. The memories Atom has, include some very happy events in both his own, and Tobio's life. He seems to be trying to make sense of it all. I cannot get episode 8 to produce any video, but expect that I shall eventually succeed. At that time, I will be more able to determine if Atom accepts this fact, or, if it continues to trouble him.
3. Does Astro know that Atlas is his 'brother'?
In the 80s series, in the last Atlas Episode, "Atlas Forever", Livian tells Atom that he and Atlas are brothers. In the current series, I am not sure that they even are brothers. The
page for Atlas says nothing of the relationship, but both are creations of Tenma.
See the relationships between Tenma, Atlas, and Atom. on the chart.I hope this helps you.
