Creator, Father, bless me.

I have no idea what's going on up there or in the future. I don't think anyone does either.
As for the argument itself, it seems to me that it says that the father's investment in his son bears fruit. If the son does a mitzvah, it means that the father's investment has borne more fruit and he deserves more reward. The assumption here is of course that the consideration is consequential, otherwise what does it matter what the son does, after all, what the father invested in him is what he did in the past regardless of the son's actions, and for that he deserves credit.