Question about the ending *spoilers

Why on earth did the necromancer guy need to go forward through time to get the baby? Were there no house servants or really anyone of the lower classes that would sell him one back in that time period? Or he could have fathered one himself with someone other than his wife.

Also, what was the purpose of him going into those other situations (shown through the flashbacks)? Just for kicks?

Maybe I'm missing some info or missed a key scene because it all seemed very disjointed and illogical.