So i reference a lot of New 52 Nightwing stuff (it's not that bad guys it gave us GRAYSON and court of owls). And for reference, my fave pairing with Dick Grayson is Helena Bertinelli and then Starfire, only I just - I can't do Barbara Gordon, but I tried to treat her nicely and avoid bashing. :) On with the story!
*refernces actual canon
What they don't know about Dick:
Those three weeks at the 'Juvenile Detention Center'?
Dick was taken to the Court of Owls to begin his training, but to avoid making a scene when Bruce Wayne asked for him, they had to replace him in the system. Dick still knows how to kill more effectively than even a member of the League of Shadows. It's why he understood Damian so well. He's kept this to himself, since he believes Bruce will hate him if he discloses it.
Why he's so happy all the time?
When he was eleven, he got a dose of diluted Joker Gas. It wasn't strong enough to show any immediate, obvious effects, but it manifested in his nervous system, and gradually took it over. It compels him to defuse detention through jokes and laughter. Dick never told anyone because he was just starting out as Robin, and Bruce needed him to be strong at all times.
What his type is?
Not redheads. Dick knows he could never pursue a stable relationship with a redhead - or anyone, really - because he would get too many flashbacks. His mother was a redhead, Kory was a red head, Raya was a redhead, Barbara was a redhead. In all actuality, though, he's attracted to people who know what they're doing, and why they're doing it. People with their purposes. Maybe because he's still not exactly sure what his is.
What his fate is?
In most universes, Dick is evil. Sometimes the successor of Deathstroke, sometimes a Talon, sometimes Two-Face. In others, he's dead. He's only seen three alternate dimensions where his life turns out relatively okay. In one, he and Kory got married and had a child, 'Nightstar'. In the second, he's still Batman, and Damian's still his Robin. In the last one, he's 'Agent 37' of Spyral, which protects the world's secrets. As for this one, he had his palm read by a Fortune Teller who said she foresaw a 'short, dark life' and told him to take caution, but live every day like it was his last. Dick took it to heart.
Why he talks so much?
Practice with English. Sometimes he still blanks out on words he should know and can only think of the Russian or Romani version. That, and he doesn't like silence. He knows no one else in the 'Batfamily' does either, so he does his best to fill it. It helps a little bit.
What they don't know about Jason?
Why he saves them if he claims he doesn't care?
Jason's a dirty liar.
Who he loves?
Jason has only ever felt an eternal familal connection to one person. Dick might have been his brother if they'd had more time, but now all he could ever be was yet another pedestal that Jason couldn't reach. Bruce he cared about, but Jason has come to terms with the fact that the man was a lying, maipulating son of a bitch - not that he'd always thought that. The replacements weren't worth a second glance. But Alfred had always been there for him. No matter what.
Who he hates the most?
In some twisted way, Damian. Jason's jealous that he gets to grow up with Dick, all happy and Batman-&-Robin together, and later Bruce, even if they have huge issues. He's sure that Bruce and Dick would kill for Damian. It hurts.
But that gets a little better when Replacement Numbero Uno tells him about the time Nightwing killed the Joker* and Tim had to rescusitate the bastard.
Who he'd kill?
Anyone who gets in his way.
(Except Bruce and Alfred of course).
Why he can't see movies?
Everything reminds him, in some way, of the pit. Which should honestly have a list of side effects. Zombie flicks make him sick, and he sees action films more than enough in real life. Romances are - no, just no. Comedy reminds Jason of him. Which leaves horror, which he also sees on a daily basis. Nearly everything else would cause him flashbacks to a) drowning in a pit of chemicals or b) being beaten with a crowbar and then blown up. Yeah. Pass. He'll take reading any day.