From his early days as Power Man, the Hero for Hire, to his time leading various Avengers squads, Luke Cage is a character who has gone through a few different changes that have seen him become one of Marvel's most dedicated family-oriented heroes. And more than anything else, Cage's time as an Avenger was what drove this change.
After serving as a Hero for Hire from the '70s to the '90s, it wasn't until 2001's Alias #1, by Brian Michael Bendis and Michael Gaydos that Cage was reintroduced in his more modern context. Cage quickly became romantically involved with Jessica Jones, with the two eventually having a child and moving in together. Luke became very protective of his new family, including the time he attacked Norman Osborn for threatening Jessica in The Pulse #5, by Bendis and Mark Bagley.
Everything really changed for Luke when he helped quell a breakout at Ryker's Island in New Avengers #1, by Bendis and David Finch. Afterward, Captain America himself recruited Cage to join his New Avengers lineup. Cage adapted to this new life fairly quickly, and he brought the team a bit more down to Earth. For example, in New Avengers #17, by Bendis and Mike Deodato Jr., Luke brought the team to a rough neighborhood in Detroit. Cage wanted to send a message that scared away criminals and allowed ordinary people to go about their lives. With Cage on the team, the Avengers dealt with a variety of problems, beyond global catastrophes. While he was on the Avengers, Luke proposed to Jessica, cementing his place as a family man. The two got married in New Avengers Annual #1, by Bendis and Olivier Coipel, changing their lives forever.
Of course, this marriage was soon to be tested. During Civil War, Cage sided with Captain America against the Superhuman Registration Act. In New Avengers #22, by Bendis and Leinil Francis Yu, Luke explained that he wouldn't register because he wanted to set an example for his daughter, Danielle. Sticking to his beliefs, Cage wanted to show Danielle that her father stood by his principles.
After the war, the New Avengers went underground, with Cage as their leader. While Cage carried on in Steve Rogers' name, the burden of leadership weighed heavily on his marriage. After the Hood and his gang of villains attacked their home in New Avengers Annual #2, by Bendis and Carlo Pagulayan, Jessica left Luke and took Danielle with her. It wasn't until after Secret Invasion that Luke and Jessica reunited, and by that time, a Skrull impersonating the Avengers' butler, Jarvis, had taken Danielle.
Cage desperately turned to Norman Osborn for help, in New Avengers #48, by Bendis and Billy Tan. In a risky move, Cage had Osborn find Danielle. Afterward, Luke barely escaped the clutches of Osborn's Dark Avengers. For the rest of "Dark Reign," Cage stepped down as the New Avengers' leader since Ronin took on the role. Still, Cage remained the heart of the New Avengers, fighting Osborn's "Dark Reign" until Steve Rogers returned to the scene.
Following Osborn's downfall, in New Avengers #1, by Bendis and Stuart Immonen, Cage was given free rein over the New Avengers by Steve Rogers. Cage and Jones were able to take care of their daughter while living in the newly renovated Avengers Mansion. At the same time, Cage assembled his own Avengers team, with friends like the Thing and Daredevil joining the group. Eventually, however, the strain of being Avengers took its toll on Cage and his family. In New Avengers #34, by Bendis, Deodato, Chuck BB, Farel Dalrymple, Ming Doyle, Lucy Knisley, Becky Cloonan and Yves Bigerel, Luke and Jessica left the Avengers to raise their daughter peacefully. It's quite fitting that New Avengers ended as soon as Luke and Jessica left. These two were truly the heart of the series, especially since Luke became the New Avengers' leader. The New Avengers gained a sense of pathos with Luke and Jessica at the center of the series.
This team was already fairly grounded, featuring street-level heroes like Spider-Man and Iron Fist. Yet with Luke Cage, an ordinary family man, as the team leader, the Avengers felt a lot more human. Cage was constantly caught between trying to raise his family and fighting for his principles. Between Luke and Jessica, the balancing act between hero and parent was pretty difficult. This struggle transformed Luke Cage as a character overall. Before, Luke was known as Power Man, the hero for hire. Alias modernized the character by turning him into Matt Murdock's bodyguard. When Cage became an Avenger, however, he became a leader and he became a true family man. This shift solidified his role in the 21st century. While Cage has joined a few Avengers teams since then, it was his time on the New Avengers that made Luke Cage the hero he is today.