J'onn is portrayed as very calm and collective in fan-fics.
J'onn has numerous powers, such as incredible strength and durability, as well as laser vision, flight, telepathy, and he can make himself invisible and phase through solid objects.
J'onn can be made powerless or even killed by fire.
J'onn has no specific equipment to speak of.
J'onn walks in on Hawkgirl while she's watching a documentary about hawks asks if she misses her home. He then learns from her that she ended up teleported to Earth from Thanagar. He sympathizes with her as he's alone too as the last Martian. He then takes comfort with Shayera in their teammates being there for them as well as the Teen Titans. He then learns from Batman that the Titans have apprehended Metallo already. Shortly afterwords, J'onn experiences an extreme headache with the others and after it passes sees that there are two Earths there now.
J'onn then left with the X-Men to investigate the second Earth. He also agreed with Flash that the X-Men each possessed great strength and abilities and agreed to the compromise of the elder X-Men, Cyclops, Beast, and Storm coming with them to investigate. J'onn then went with them to New Genesis to stop a controlled Superboy and Raven, along with two controlled X-Men, Charles Xavier and Jean Grey. While the X-Men distract him, J'onn enters Xavier's mind. There, he enters a derelict version of the Mansion to see Xavier chained to the wall. J'onn then frees Xavier, and they defeat the robotic mummies Apocalypse sends to keep Xavier imprisoned. Afterwords, J'onn and Xavier both enter Raven's mind to free her. Inside Raven's mind, they beat down an apparition of Raven's father Trigon and followed Raven's happiness through the pyramid into a maze. They then followed Raven's timidness to the end of the maze where Raven's bravery saved them from two robotic mummies. J'onn then kept the one who was controlling Raven and the others, Apocalypse, busy while Raven's inner-child saves Raven. She then frees herself. After that, J'onn went to the Mansion with the others to wait for Darkseid's next attack.
Knowing the TeamEditJ'onn was later at the Watchtower and restrained Superman when Darkseid arrived and asked for help in helping him against Brainiac and Apocalypse.
TwilightEditJ'onn can't believe when Superman exclaims that he wouldn't mind of Apokolips is destroyed. J'onn then convinces Superman to assist Apokolips by pointing out that if they let Brainiac continue, he would be a giant mar on Krypton's legacy. J'onn then went with Superman's team to Apokolips and remained in the Javelin while everyone else fought. J'onn then uses the Javelin to destroy several of Brainiac's lasers. When Brainiac and Apocalypse retreat, J'onn pilots the Javelin while the others re-board and follow their ship. When the ship disappears in an asteroid, J'onn's the first to realize that this isn't an asteroid, and they end up being pulled into what is revealed to be Brainiac's main base by a tractor beam.
J'onn then explains that all the controls were being overridden. He then assured Hawkgirl that it was possible Thanagar was inside Brainiac's archives somewhere. Martian Manhunter then fights Brainiac's defenses when he arrives. J'onn then fights an army of Brainiac copies led by Apocalypse until he's blasted unconscious by Darkseid's Omega Beam. His blood sample is then taken by Sinister. J'onn then recovers and wakes Beast Boy up after a few minutes. J'onn then explained that he couldn't find Superman with his psychic abilities, which would lead to him being either unconscious or dead, which earned him a shout from Superboy. J'onn then flew off in an attempt to find Superman. J'onn then offers looking up information about Thanagar, but Hawkgirl declines in favor of finding Superman. J'onn then arrives with the others and attempts to shield them from attacking Brainiac copies. After Superman is freed, and Brainiac begins to self-destruct, J'onn went to the Javelin with everyone else except Superman as he carried an unconscious Hawkgirl. J'onn then reluctantly to go off without Batman, replying to Jim that he likes to do things alone. They then make it to New Genesis as Brainiac explodes, taking Darkseid with him, while Batman, Superman, and Superboy escape via a Boom Tube. When they see that the New Genesis citizens have survived, J'onn comforts Hawkgirl by saying someday she might find her place in the universe.
Tabula RasaEditWhen Xavier was rendered unconscious from an attempt to use Cerebro to find Lex Luthor, J'onn confirmed that he was going to be fine and did the same thing Luthor did, but he was only able to determine that Luthor was in an area surrounding LexCorp. Martian Manhunter later went to the Titans and younger X-Men's aid when they faced an android named Amazo. He ended up scanned by Amazo and saved when Batman drove him off with Kryptonite. Following that, Martian Manhunter confirmed that he sensed Luthor in a LexCorp warehouse. J'onn then monitored the next fight with Amazo when a recovered Xavier arrived, and he took Xavier there where he revealed that Luthor was using him. Amazo then flew off. J'onn then arrived in time to see Amazo spare Luthor and fly off. When Flash asked where he was going, J'onn remarked that he was going where gods belonged.
Only a DreamEditLater, J'onn was taking a nap before a breakout at Stryker's Island that involved several supervillains. When Kitty asked what J'onn was doing, he explained he was taking a nap. At Stryker's J'onn helped Superman fight Grundy which had limited results. J'onn then went with Superman's idea and knocked him into the air. After Grundy's defeat, J'onn confirmed that everyone who broke out had been captured. J'onn then got a message and met up with Batman and Robin at a hospital where an escaped prisoner, John Dee, had placed his wife in a nightmare she couldn't get out of. J'onn then began to read Penny's mind. All J'onn can figure out is that John now calls himself Dr. Destiny. As he tries to get Penny out of it, he informs Batman and Robin that Dee wants them too.
When the rest of the League, the Titans, and the X-Men except for himself, Xavier, Beast, Robin, and Batman were attacked in their sleep by Dr. Destiny, J'onn used his formidable telepathic abilities to rescue his teammates from their various nightmares, and to bind them together to fight Destiny's mind control.
Martian Manhunter then said good morning to Conner and flew off when Conner was two.
Three years after this, Martian Manhunter sparred against the other Justice Leaguers and flew off to deal with Darkseid when he arrived.
When Darkseid attacked again, Martian Manhunter was part of the League to attack, and he tried to calm an excited Hawkgirl down before the fight. He then retreated when Darkseid arrived as he claimed that they didn't have a chance against him without Superman.