Kaptain Briton was an enemy of Captain Britain.
Summoned along with the rest of "the Captain Britain Corps" to Merlyn's funeral on Otherworld, Kaptain Briton noticed the strong resemblance between himself and Captain Britain of Earth-616. During the wake he continued to watch his counterpart.
Kaptain Briton ran away from his home dimension, angering his somewhat unstable paramour, Mastrex Opul Lun Sat-Yr-Nin. She despatched armoured hunters to bring him home.
During Captain Britain's first fateful encounter with Meggan, and the ensuing battle, both were unaware that they were being spied on by Kaptain Briton; it is possible during this particular fight that Kaptain Briton altered Captain Britain's costume's electrical aura to match his own, as almost immediately after this incident Sat-Yr-Nin's hunters began to attack the wrong Captain.
Extradimensional hunters attacked Captain Britain in his mansion, and overpowered the hero (who was not wearing his power-enhancing costume) before being stopped by the mental powers of Betsy Braddock. Meanwhile, watching outside the window was the lurking form of Kaptain Briton.
While Brian Braddock told his sister a potted history of his lives and times as Captain Britain, the two failed to notice the continued surveillance being carried out by Kaptain Briton.
Roma agonised over having carelessly brought both versions of Brian Braddock/ Byron Bra-Dhok together at her father's funeral, and reviewed the recent build-up of events that was leading to the showdown between the Captains. However, she felt she could not intervene the way her father used to.
Byron Bra-Dhok calmly walked into Braddock Manor and appeared about to attack Betsy when Captain Britain, appraised finally of his doppelganger by Gatecrasher's Technet, smashed through the window. Byron assumed his costumed identity and the two men started a highly destructive battle through the different levels of the mansion.
The combat made its way into the subterranean caverns which housed the Mastermind computer, where the heroic Captain appeared to finally gain the upper hand. A few seconds later Captain Britain handed over his unconscious opponent to the Technet—Yap confirmed the victor was Earth-616's hero, and Alison Double scanned him at Gatecrasher's behest in order to make certain. Betsy, the person who knew him best, could not help as her powers were still unusable after being dampened by Elmo. The Technet departed for the villains' home dimension with their captive. Her powers still blocked, Brian offered to walk his sister Betsy to her room. But as soon as they were alone, he tried to rape her.
Brian Braddock awoke in the dimension of the Empire of Briton, remembering how his counterpart knocked him out with a device of some kind just when he thought he had won the battle, and then swapped costumes with him.Meanwhile back on Earth-616, Betsy was horrified to discover that Byron Bra-Dhok had fooled Yap and Alison, and the man attacking her was not her brother. As he attempted to rape her he discovered to his cost that she was not as powerless as he assumed; she ripped the memories of his murdering and torturing for the Empire from his mind, then threw him around the room (presumably using his own flight powers, as she wasn't a telekinetic) before finally frying his mind, killing him.
The real Brian Braddock returned home seconds later thanks to the assistance of the Technet, to find his sister sitting next to the burnt out corpse of Briton. The Mastermind hologram arrived and took the corpse away for proper disposal.