While Red Hood has always cared about Nightwing, it’s very rare for him to outwardly express it. On one occasion, Jason Todd got painfully close to outright telling Dick Grayson how he truly views him, but he wasn’t quite able to say it.
Jason - and the entire Bat-Family apart from Batman himself - had assumed Dick to be dead for quite some time. Dick was unmasked to the whole world by the Crime Syndicate in the Forever Evil crossover event and was subsequently killed. Although he was revived, Bruce forced him to go undercover in the spy organization Spyral and to let the world keep thinking that he was dead. No one was allowed to know that Dick was alive, and unfortunately, this also included Dick’s fellow Robins and Bat-Family members.
Dick returns to Gotham in Grayson #12, written by Tom King with art by Mikel Janin, and when the Bat-Family finds out that Dick hadn’t died, reactions are mixed. Barbara is disappointed but not surprised, while Damian is thrilled. However, Jason is furious. He greets Dick with a fist to the face and exclaims that he went to Dick’s funeral (which is important, because Dick didn’t go to Jason’s). He tells him, “I don’t care what Bats told you, you don’t do that to your - you don’t do that to another Robin!”
Jason was clearly about to refer to Dick as his brother, but he stopped himself, probably for a variety of reasons. He’s already got some serious family issues, so calling someone his brother out loud in the first place is uncommon. He had gotten to that level with Dick, but then Dick’s perceived betrayal made Jason hesitant to call him a brother, which is heartbreaking. In addition, death is no laughing matter to Jason. For Dick to use death as merely a cover for a mission and treat it as something trivial was likely a major insult to Jason, whose death shaped his life.
He didn’t outright say it, but it’s clear that Jason views Dick as his older brother. Luckily, since this incident, they’ve rekindled their relationship, including recently in Nightwing Annual 2021 #1 written by Tom Taylor with art by Cian Tormey and Daniel HDR. Even though he couldn’t say it at the time, it’s undeniable that Red Hood has always cared about Nightwing as his brother.