Luca isn't a good person, he never was and would never be. He's the son of a fallen angel, an angel who was kicked out of heaven for his sins.
His father then came to earth where all banished angels stay, some would go down to Hell and kneel for their new King, Lucifer while others just stay on earth.
Luca's father kneeled, he made his son grow up in hell, literally. Luca was raised to act as a bad guy, to steal, take, kill, hit, anything for his pleasure, and to keep his king happy.
Heaven and redemption were never on his radar, he didn't care, he didn't want to go to heaven, he's happy in hell.
That's how life went on, for centuries and centuries, until Luca grew up and became one of the most scared fallen angels to ever walk the earth. Some would say he fell on his own, others say he's the son of a demon and angel, rumors went as bad as to call him Satan's son.
Neither Lucifer nor Luca commented on the rumors being true or just some overactive imagination of the people who're afraid of Luca.
Lucifer has no sons, he got no kids, the heaven cursed him with the loss of his fertility when he fell from the heaven, he's forbidden to step foot on earth or heaven, his only and last land is hell, he's the king, the ruler, why would he want to leave.
Luca never had a weakness, he never kneeled for anyone not even Lucifer, he refused to kneel or show vulnerability. That's what everyone thought, what heaven and hell believed until the pages of destiny wrote a new love story, when things get written there, only god can change the destinies.
Ella the daughter of an angel and a human, she was raised on earth never knowing what she was, never understanding why things happen to her, why some people hated her while others say they can see heaven in her blue eyes, blond locks, and snow-white skin.
Angels, they grow up in heaven or hell, they'll take around a hundred years to grow up physically, another hundred years to reach adulthood mentally. Ella's human side made her body grow up, she's nineteen in human years, her body reached its maturity, but on the mentally and angelic side, Ella was only a baby.