Demon's Revenge

The half-demon children are now grown up. They are all happy and living normal lives in total ignorance of their heritage.
The ripple that passes through Hell at the release of Gage's powers alerts Grubel to the possibility that his son has been returned to him. He rubs his hands in glee and sets out to find him.
To his surprise, he comes across Gage, whom he didn't know existed but senses no Demonic evil in him. He continues his search for his beloved son, Graham, whom he was teaching to use his powers when Graham was a small child. Grubel catches him up with what happened seventeen years ago, causing him to become furious at Mandy for binding his powers and June for altering his memories of his father and the fun they'd had together.
Whoever came up with the saying that 'Hell hath no fury like a woman scorned' had obviously not come across a half-demon adult finding out his heritage had been stripped from him and his memories of his true past replaced with false images. The hatred for Mandy and June leads him to work with his father to exact extreme revenge on them, using whatever means available.