Nightwing
Although Nightwing is commonly associated with Batman, the title and concept have origins in classic Superman stories. The original Nightwing in DC Comics was an identity assumed by alien superhero Superman when stranded on the Kryptonian city of Kandor with his pal Jimmy Olsen. Drawing inspiration from Batman and Robin, the two protect Kandor as the superheroes Nightwing and Flamebird. Following the Crisis on Infinite Earths continuity reboot in 1985, Nightwing was re-imagined as a legendary vigilante from Krypton whose story inspires Dick Grayson's choice of name when he leaves behind his Robin identity.
Nightwing
Saved by the Justice Society, Nightwing recovers with Barbara at his side. As soon as he's able to walk again, Batman asks him to join him and Robin in retracing Bruce's original journey in becoming the Dark Knight. While Nightwing is hesitant, due to his engagement with Barbara, she encourages him to go and returns his engagement ring so he can make an honest decision for himself. Barbara feels that it is important he rediscover himself, and until he does they're not yet ready to be married. They part on good terms, though before he departs Dick leaves her an envelope containing a photograph of them as Robin and Batgirl, along with the engagement ring on a chain and a note promising he'll come back to her one day.