You know, most of the time when anime has characters be terrible parents they're also horrible dickbags in general.
But what about great people that just suck at parenting? How many examples can you think of?
You know German's failure as a parent has a lot to do with the fact that being a Makai Knight is a thankless, tough profession he had to prepare his son for.
But it'd really help if they shared any interests whatsoever. Or alternately, if he didn't want to stick his dick into everything that moves...
I would have been cool if he actually took the time to talk to his son about his mom, it probably wouldn't have resolved his anger but at least it would've gave them common ground but nope had to leave him to his own device.
More or less. Hell, he has most of "Lancer" in his personal name, so it's no wonder he has misfortune really.