If it can find a way to introduce Nightwing properly, Titans season 2 could achieve greatness. The first season of Titans finds Brenton Thwaites' Dick Grayson in semi-retirement as Robin, although he'd pop on the suit whenever some extra-curricular work was necessary. Grayson's main arc in Titans season 1 concerns his damaged relationship with Bruce Wayne, with the former Caped Crusader and Boy Wonder evidently not on good terms. In a symbolic move, Grayson even burns the Robin outfit he usually carries around with him, heavily suggesting to the audience that the original version of Robin is no more.
Brenton Thwaites has teased that his character will be getting a brand new suit in Titans season 2 - but one relating to Nightwing, rather than Robin. Nightwing's introduction in Titans would certainly make sense in relation to the character's comic book history. After breaking away from Batman, Grayson switches from Robin to Nightwing as a way to move on from his past. With Bruce Wayne set to make a proper appearance in Titans season 2, the issues between the Dark Knight and his former sidekick will undoubtedly be addressed and this will perhaps facilitate the evolution from Robin to Nightwing. In terms of age, Titans' Dick Grayson is also perfectly placed to strike out under his grown-up superhero persona.
All indications suggest that viewers will see Dick Grayson become Nightwing in Titans season 2 and this could have a profoundly positive impact on the series. One of the key criticisms leveled at Titans' first season was a distinct lack of screen time showing the young heroes operating as a unit fighting bad guys and Grayson's arc often appeared to be gravitating away from crime-fighting altogether. To roll out a new Robin outfit now, after so dramatically destroying his old one, would make little sense, but moving from Robin to Nightwing would allow Titans season 2 to adopt a more traditional take on the Teen Titans story, with the Boy Wonder rediscovering his love, and perhaps even his need, for vigilantism.
Secondly, Nightwing fits far more naturally with Titans' gritty, adult tone than Robin ever could. Often unfairly painted as a figure of ridicule, DC's original Robin has far more to offer than his enduring appeal to younger fans might imply. However, while Robin has certainly enjoyed stories with more mature themes (mostly Grayson's successors, rather than the original Robin) the character is not readily associated with the violence and moral line-walking seen in Titans season 1. Nightwing, on the other hand, is far better suited for this tone, with plenty of violent moments in his comic history and a reputation as a more "serious" superhero.
It's also worth considering that a second Robin already exists in the Titans world and Curran Walters' Jason Todd has been bumped up to a series regular for season 2. Balancing two opposing Robins would be a tricky feat, but allowing Dick Grayson to progress into Nightwing ensures Titans can bring the best out of both characters. Viewers would get to see more of the unhinged, uber-violent Jason Todd, but without stepping on the toes of Grayson, who would've adopted his own new persona - one completely separate from his days under the wing of Batman.
Looking beyond Titans season 2, the resentment Dick feels for Bruce Wayne can't remain a central tenet of the character forever. At some point, Thwaites' character is going to have to move on and this can't happen while he has any connection to the Robin title. Dick must also overcome his fear of becoming the same no-rules vigilante he resents Batman for turning into. Introducing Nightwing in Titans season 2 would tick both boxes.
Titans season 2 premieres September 6th on DC Universe.