My brain is fried, I can't write more than half a page and even that no matter how much I rewrite constantly looks like crap.
So here is in short the idea I was working on, if anyone wants to use it...
Sparda is a demon hunter posing as regular private eye under the name Jack Conner. The time is couple of years before he meets Eva, and the place where he has his business is the neighborhood where Dante will be living. He lives alone, and has a middle aged woman named Ruby come to clean every now and then. Ruby's son is Fredi, a teenager who dreams of opening a big restaurant, though he is actually Fredi from the anime so we know how it turns out.
Morrison, that guy from the anime in his teenage years, shows up in the neighborhood as a lowest ranking member of a mafia-style gang, pulling ****, doing the assignments they give him, and crosses path with Sparda for the first time when a guy he was supposed to kill turns into a demon, though he isn't able to see Sparda's face. He is brash and loud-mouthed, a typical rebellious young male. He however holds a secret. When he was a little kid his father was murdered by the boss of this gang, and him and his mother had been on the run ever since. Morrison now came back and infiltrated the gang, trying to climb rank until he can reach the boss to kill him. What he doesn't know is that the murdered man wasn't his father, his real father is the gang boss, a man that dabbled in dark craft and wanted to sacrifice his son to the demons in exchange for becoming one. The murdered man was the one that got the mother and baby Morrison to safety and he took upon the role of father to both prevent gossip and to give Morrison an illusion of a normal family.
But now the boss knows Morrison is back and with his own mortality pressing him harder with each day, he wants to finish what he started. So he calls Morrison to his villa on the coast under excuse of wanting to meet this new blood that will help the gang stay strong. The evening before he has to go to the villa, Morrison gets drunk in the bar and Sparda has to drag him home, finding out about Morrison's agenda. The boy leaves the next morning with one hell of a hangover, and Sparda secretly follows him. In the villa creepy things happen, gang members turn out to be demons posing as human, Morrison gets dragged into the basement level where a special shrine is made for demon worshiping and is prepared to be sacrificed. At this time Sparda is fighting his way through demons, reaching the shrine just in time to stop the dagger from reaching Morrison's heart. Few drops of his blood however fall on the altar and the boss is able to make a faulty, incomplete transformation. He is defeated by Sparda, who burns the villa and every demonic creature left in it and takes unconscious Morrison home.
With the gang boss dead, there is no revenge anymore, and Morrison is left without a purpose. So he decides to work for Sparda, gathering intel on demon activity and other stuff, and with that he also makes a name for himself in the mercenary community, becoming a respected agent. His partnership with Sparda is not a long one, the devil disappears one day without a trace, just a rumor is told of a blond woman that could make his eyes gleam in a different way.
Epilogue would be years later with older Morrison bringing work for Dante, having a nostalgic moment when he sees him at the desk.