[It was a little bit of both, really. At first it simply felt right when he was younger: it was what his father did. But then David made Mia and the others, it was more of a desire to be able to understand how it was done and help them if anything bad were to happen.]
With all the worlds there are I doubt anyone would ever be able to get up to speed.
[After all, despite thinking that they were quite similar, the technology in his and Tony's world is still a little different.]