DF

DF originally comes from Final Battle, where he is the Avatar of Arek Lumina-Weise. In ITM, DF has been an antagonist in many games where Arek has been a protagonist.

ITM 3
In Tower ITM, DF was a member of the Twenty-Four. Apparently, Frank Higgs had somehow existed in the real world and cloned DF from Fred's genes, anticipating that Fred's Magi genes would be nascent. With his Magi powers and the power of Wireface, DF was capable of destroying every New Brave.

While the team never fought DF knowingly, he was in fact the Nezumi King, and was preparing plans to free himself from Wireface's control or gain some more autonomy. In his guise as the Nezumi king, DF revealed that he had bankai and massive interdimensional powers. Presumably as a member of the Twenty-Four, he had his own Ultima attack.

ITM 5
See also: Emperor Arek

DF did not exist as a full person in ITM 5. Rather, he was part of the Soultwisted persona of Fred, after he had fallen into evil and madness. DF co-existed with Emperor Arek, as well as the personalities Arek used to trick others (feigning his former Arek personality, pretending to be Alchn'aa, Lord of the Hunt, Aizen's personality within him, etc.) It was the spiteful DF persona who destroyed Gill's city after having promised Black to leave it alone.

ITM 7
DF reappeared in ITM 7 as a Twenty-Four member. Arek initially planned to use his Sylar abilities to absorb DF's knowledge and power into him, but was unable to do so as he did not get a chance to fight DF at that time.

Later, in the Dark Tournament, DF conceded in order to avoid being fused into Arek forcefully by Arek's special fusion attack. However, when Quixotic Unity occurred, Arek automatically fused with DF anyways, powering them both up to Universal Magi power. After that, DF became part of Arek's enlightened psyche.

ITM 8.3
In his first appearance not as a member of the Twenty-Four, DF in ITM 8.3 was actually the genetic clone of Arek, unbeknownst to the both of them. DF publically supported Kridos and his fellow Scions, but privately wanted to kill most of his comrades, including Frederick Ulysses Mario and Zeke. He had managed to keep the true extent of his sociopathy and evil from his adoptive father.

DF accompanied the group on the mission to Zeal. He raped the Zeal Defense Force commander to death then got the access codes from her cells, taking her personality. His disguises failed to trick Belthasar, however, so DF simply attacked Belthasar's Nu and kidnapped him. DF was planning on offering Belthasar his freedom if he assisted him surreptitiously against Kridos.

Afterwards, DF was sent throughout time with the rest of the Scions. He was unable to use Quick and the Dead against The Flash, but was able to turn around Mephiasu's defeat against Mike. When he saw what Kridos had done to his father, he had feigned indignation, but he was in fact impressed at the degree of evil Kridos had shown, and intuited that Kridos had in fact gone far further down the path of evil than anyone had expected.

DF had planned to go to Zeal and take Lavos' DNA. He had managed to speak to Dr. Myuu and create a Hell Android copy of R. Daneel, pitting the two against each other and absorbing both in the aftermath.

DF attempted to infect his genetic father as a backup plan, but this plan backfired and gave his genetic father the powers of the Harmony Magi.

After Kridos' defeat and the victory of the Saints, DF launched his final spoiler plan: Destroying himself to cause a cascade similar to the Coming of the Rifts.

ITM 8.6
After this plan was launched successfully, DF and the Scions appeared in a new universe, apparently connected to the prior one by virtue of inhabitants of this world telling the story of the other. The Scions began their plan, but whether it would be world conquest or world destruction was still up for grabs.

The Scions attempted an assassination of the President. DF in particular was insistent that this attack would cause panic and increased violence as a counter-attack, so he made sure to kill as many innocents as possible. However, the Scions were forced to retreat, unable to assassinate Obama.

After the first Obelisk was destroyed, the heroes found out from SETI that a blanketing signal that would interfere with mentalic signals was being transmitted by someone. This would prevent DF from using his R. Daneel powers to manipulate events with his psychic powers, though DF could still use psychohistory to anticipate the present direction of events and find ways to change the trajectory of history.

DF then appeared before the party was about to access the second Obelisk. He revealed that he had killed the heroes' families and trapped them in soul gems. He offered to return them, arguing to the team that they might as well give up and simply live out their lives before the end with their families. The heroes agreed to give him a music box from the Black Vault but attempted to sabotage it. This failed, however. DF only needed some information from the box: He would use the Litany to become Wireface and a member of the real world.

DF apparently is expecting Arek to make a counter-move that breaks some rules of the world, perhaps something on the Forbidden List. It is unsure what he intends to do with this, or even if this is actually his plan and not a lie.