Ada Shepard
Ada Shepard was the Lead at the old S.T.A.R Labs branch in Metropolis for some years before leaving to help Meta-Human children master their powers. Though she quit, her ties were strong to S.T.A.R Labs as she was often approached on subject matters classified Level 2, going up from 7 to 1. With that power, Ada often used it for non-violence, even though a number of S.T.A.R Labs focused on weapon research.
The Justice Teens and Ada have had a long relationship, as she would keep them out of trouble in hopes they would keep each other safe. Sometime in 2008, Ada saw them as dangerous due to recruiting Frost Teen and decided to keep Meta-Human adolescents out of their hands. It would take some time for Ada to trust the Justice Teens around her students, and by that time both teams had already met on a few separate occasions. Now if needed, Ada will assist Blurr and his league, just as long as their goals are pure and straight.
Academy Students
S.T.A.R Labs had given their lead Meta-Human specialist, Ada Shepard, the resources to develop a facility to train and teach young Meta-Humans. The school would become known to be Shepard's Academy of Mastery and Learning, and act as a focal point for the Meta-Human community. The student body, along with some staff, is built up of many Meta-Humans with powers ranging from the fantastic to the mundane. Once the students have graduated, they either leave or become Squad Leaders, teaching the next generation to use their powers.
A small number of original students were taught by the Justice Teen Psi Lad and many more would come to meet the rest of the league during their own missions. Many are known to respect and admire the J.T, wishing to one day join their ranks, while others would rather have nothing to do with them and follow their own path which often leads them to joining Maximum Zero.
Patricia Nightly
Patricia Nightly is a United States, Government Agent, and X-liaison of the Justice League. Originally tasked with the pre-threat taskforce, First Defense. As she grew closer to the Meta-Human community, she would run across individuals such as Elizabeth Right, and even survive an assassination attempt on her life from a future Kid Nitrro. Finding interest in the young speedster, she mistook him for a young Kid Blurr, and in 2007, had sent Mockingbirdx to kill him. After noticing his friends and his age, Nightly placed Mockingbirdx into Blurr's team to watch over them, until she would later confirm that Blurr was not the speedster she had encountered.
Nightly can be viewed as an aggressive leader, usually utilizing lethal force on her enemies. While she assist the Justice Teens in their adventures, she had prepared herself to take them down if necessary. Until that day however, Nightly acts as their legal guardian, keeping their secret identities from going public, and even secretly recruiting a few of their members into First Defense.
Edward Hunnigan
A Vampire that's been around for hundreds of years, Edward Hunnigan's been standing in the background of history. Part of the Hunnigan clan, Edward would work on the lower East coast of America, mainly in Georgia. This is where he would meet the original Justice Teens, and more importantly, Kid Blurr. The two would form a friendship, even after the loss of the team. Though the two would break off during the Brainiac invasion, Edward would later find Blurr, and try to use him.
Edward Hunnigan is seen as scum of the Earth, involved in Human trafficking, ambushes, and night time, rave-feeding orgies. Only those closest to him would know however, that Edward has strong ambitions, and the means to meet them. He wants to put all Vampire clans under one banner, his own, and is known for using the Blurr to help. Though he's come close to it, each time brought him ever closer to being destroyed by individuals like Theodore Xater and Frost Teen. Seeing him for his worth, and vies versa, Kid Blurr contacts Edward Hunnigan whenever Vampire related events happen, or if anything is going on in the dark, seedy, underworld. That being said, their relationship as a whole is viewed as "shaky".
Peace
Peace is an old friend of Kid Blurr before he joined the original Justice Teens. After they're separation on the island, Peace would go to return home only to find Patricia Nightly waiting for him. She recruited him into First Defense, from where he would keep an eye on his old friend. In 2011, the two would reunite soon before Blurr's death.
Though a teen himself, Peace had dedicated using his powers to protect the Earth with First Defense. As a friend of Blurr, who is also leader of the J.Ts, he's known for coming to their aide whenever called upon.
S.T.A.R Labs
S.T.A.R Labs had gotten mixed up with the Justice Teens in late 2007, after Mockingbirdx saved Ada Shepard near the Science Spire. Since then, she's kept a constant watch over them along with the rest of S.T.A.R Labs. With their help, they were able to help the Justice Teens get a hold of their powers and tech that would come in hand. One such device would be the trans-dimensional traveling space station the J.Ts call Sky Front.
The Metropolis branches of S.T.A.R Labs are best connected to the Justice Teens, as they are both well versed with Meta-Human biology and science. One such instance in which S.T.A.R Labs had assisted the Justice Teens was in 2009 when Kid Blurr had lost control of his powers and attacked Detroit. Other lead scientist would step up such as Michael Keeton and Christopher Groph, both men who made leaps into understanding and utilizing Meta-Human energy and teaching Blurr about the unknown scenes of the Speed Force.
The Justice League of America
The Justice League of America is a team comprised of Earth's most powerful Heroes, and maybe even the Universe. Lead by Superman, Wonder Woman, and Batman, the J.L.A have trained many new heroes in their day, keeping them safe from the dangers of the world until they were ready. The Justice Teens however, were made of independent teen heroes with no ties, creating a few issues for the League. Though they've agreed not to intervene in each other's work, the Teens and Leagues have been known to work side-by-side to fight off entities such as Darksied and Dimitrios. Many heroes of the League have been known to try and mentor members of the Justice Teens, with only a few declining their help.
The first encounter between the Justice League and Justice Teens would be in 2007, during a riot at Belle Reve. The next time, the two groups would fight, leading to the incarnation of the Justice Teens, and an all out assault on the Watchtower a few days after. After having a deal brokered by Patricia Nightly, leader of First Defense, the J.L.A and J.T.A have since followed the goal of protecting Earth, even though they don't see eye to eye.
Yahnni
Yahnni is a high ranking member of A-Game, and a constant ally of the Justice Teens of America, even though many of A-Game despise the team. His young age gives him a better connection with the members of the team, though he is still a threat to those he views as a threat. A man of honor, Yahnni is not known to fight dirty, and usually comes out on top, despite the odds he faces. Trained in the special branch of A-Game, Yahnni, is capable of standing toe-to-toe with many Meta-Humans.
It's unknown exactly when Yahnni would join A-Game, or if Yahnni is his real name, however, his name has been put at the top of many countries "Most Wanted". His first encounter with the Justice Teens would be in 2008, after a raid on S.T.A.R Labs. Mainly due to the capture of the Justice Teens by his own organization, and painful experimentation by their buyer, Elizabeth Right. Taken the organization into his own hands, he would help them however he could, but would not refrain from fighting them. When Paine attacked the Academy, Yahnni took a small platoon of A-Gamers with him to help Maximum Zero and Kid Blurr, fight them off.
The Pac
The Pac is a New York street gang lead by Nancy Stelopli, a Meta-Human with light based powers. First meeting the Justice Teens not long after the death of Kid Rager in 2008, the two groups did not get off on a great start, nor did they try to fully repair their relationship. That being said, after a mission in New York, Kid Blurr and Nancy worked together and now carry a somewhat flirtatious relationship. Whenever the J.T needs help in New York, the Pac is sure to help; for a small price.