In the comics, he features a lot in the story where Grayson becomes Nightwing, both in flashbacks where they show his past and in the present as the main villain. In the story, Deathstroke is presented as someone Grayson could have potentially turned out like if circumstances had been different and if he had different people around him (it should be noted that Slades ego played a big part in him ending up how he is too). Deathstroke offers a good look at how even heroic individuals can go down a dark path under certain circumstances and how important people in your life are at influencing who you become.
Grayson mentions his parents, Batman, Superman and Starfire as people who all had a positive influence on him, and in Batman and Starfires case, stood by him during difficult times. He mentions how they all played a big part in making him who he is. In the same story, we learn through flashbacks that Slade had no family. He was betrayed several times by the army, who he lived for and was willing to give his life for, and him and his friend were almost killed because of this. This is very different to how Bruce treated Dick, as he would never have betrayed Dick like the army did Slade, as he cared for him deeply. Unlike Starfire, who stood by Grayson during difficult times when he was with the Titans, Slades wife left him (she was right to), which played a big part in making him such a cold individual. His close friend Wintergreen was all he had left. He didn't even become a villain or target heroes until his son died, whom he wanted to honour (another similarity he has with Dick, as well as Bruce) by completing his sons contract with an organisation called H.I.V.E, which was to capture the Teen Titans.
It would be nice to see that part of The Judas Contract storyline be adapted if they ever decide to tell that story.
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