Ok Dante is from the games Devil May Cry 1-4. He's a demon hunter who happens to be a half-breed of demon/human. He's also Vergil's younger twin brother and Nero's uncle. Sadly you have to read a hard to find novel to learn about Nero's link to Dante.
In Elyasia, Dante found his way into the realm after learning from a weak devil(demon) that his brother was in seen in Elyasia. So being Dante, left his shop to find a way into that realm. Weirdly he didn't until his girl, Tara told him. He didn't question her on it since she was his long time link to his twin.
When he got into the strange realm, he meet with an odd girl, Mira. Sadly she didn't like being called odd and kicked him. To make him even more confuse, She told him that he was so much like her sister's half-breed. So he asked her if she meant Vergil which she nodded.
Sadly it took Vergil almost killing him(again) to get Dante to stay in Elyasia, to Vergil's dismiss. It may it even more sad, Mira took a liking to this half-breed which annoyed Sinta. Just how many 'knights' does she need? XD
In short, Dante become a 'knight' after losing to his twin.
Dante is dating Tara(Salya's oc).
This Dante will be a mixed of DMC1 and DMC2. So... yea..