Headcanon based on the spoilers: In the novels Krichevskoy left Laharl in the care of Yasurl and Vesuvius for a hundred years so that he could take care of Sicily as an infant in Celestia and have time left to do his Overlord duties.

I think this mostly because I can’t picture Krichevskoy being so stupid as to leave Laharl when he needed him the most unless he had a good reason.

I guess in the game he is left in the care of Rainier for the same reason?