OKAY SO-
Wild speculation about Corbeau possibly being Giovanni's bastard below the break.
With the assumption that Corbeau is Giovanni's bastard who he ultimately decided to not claim- he still made some token attempt for an amount of time.
I'm going to say that it was the time after Corbeau's mother was no longer able or willing to care for him. Some things have to be assumed, just from the structure that's provided by Corbeau's confirmed and implied story. His parents were not around (dead, ill, or deadbeat), at some point Giovanni put some token effort forward to provide for Corbeau in a way that left a Lasting Impression, and after that Giovanni fucked off to go actively neglect his other kid on the other side of the world. (But in a way that seems to have not ruined Corbeau's opinion on him. Which could mean everything or nothing at all, depending on how you read his still existing respect for Lysandre)
So, Giovanni had a one night stand with a Kalosian or someone who fucked off to Kalos afterward. Fast forward a couple of years and for some reason he's in Kalos again (he's into myths and legends and the idea of a fuckoff big weapon might hold value for him. Assuming this isn't just regular mob shit.) Somehow, he becomes aware that his previous one night stand had a kid and the timeline and familial resemblance lines up enough for him to give guardianship a shot. (Or maybe it was regular guilt or regret. He experiences those sometimes.) He keeps the kid fed and dressed and indulges the scowling little thing with stories about powerful pokemon to keep him from asking too much about what team rocket does. I think, more than anything, he conveys to the kid that while a lot of things can be done above board, having a reputation is it's own kind of power.
These lessons land funny in the brain of a child who will develop a buckwild sense of civic duty and responsibility. But this is before Lysandre enters Corbeau's life and before Giovanni leaves it.
When he does leave, Giovanni gives just enough reason that he has to go and cannot take Corbeau with him. Just enough to make Corbeau think that responsibility to one's home is important above everything to the one adult that's treated him well.
Ultimately, Corbeau gets the aesthetic and some incorrectly interpreted lessons from Giovanni and very little else.
But Corbeau had so little to begin with that the weight of these things irreversably altered the trajectory of his life.
