I don't get why you retards keep pushing this retarded mind control theory with Craig/Phos/Pads.
The reason Craig turned into such a dick goes all the way back to his identity issues. He spent hundreds of years being controlled by a parasitic sibling who he had a poor relationship with at best and when they finally go away he's lost and on his own and doesn't know what to do with his freedom. Phos helps him along by having Adamant give him a new name and just treating him as their own person and not the leftovers of Ghost.
Fast-forward to the meeting with Aechmea where he brings up that Ghost hasn't entirely left Craig and has been subtly influencing his actions over the last 102 years and that by extension EVERYTHING Craig thought has been done independently and on his own is now tainted by the ghost
of his dead sibling literally hanging over his shoulders. Now that he's finally free of any unwanted influences, he wants to distance himself from it as much as possible in a bid to find his true 'self' which involved acting out harshly to everything Ghost and Sensei cared for.
We should probably expect a new name within a chapter or two chosen by himself in a effort to show independence.
Everyone is so fucking tragic in this manga man.