Doctor Alistaire Stuart and his sister, Brigadier Alysande Stuart, were the founders of the Weird Happenings Organization (W.H.O.), a group that investigated paranormal activity.^[3]

They investigated a mysterious train from an alternate Earth that had appeared in the place of another, carrying an alternate Nazi version of Moira MacTaggert. This led him to meet the British superhero team Excalibur. Attempting to return the train's passengers to their proper reality, Alistaire and Excalibur accidentally ended up traveling through various realities of the multiverse, searching for a way home.^[4]

The Excalibur member Shadowcat developed a crush on Alistaire of which he seemed blithely unaware, while he found himself attracted to Shadowcat's teammate Rachel Summers.^[5]

Some time after their return from this adventure, Alysande was framed for leaking state secrets to S.H.I.E.L.D. and then killed by Jamie Braddock. S.H.I.E.L.D. director Nick Fury met Alistaire at the funeral and told him that his sister was framed. Alistaire found out that the R.C.X. agency had framed Alysande. W.H.O. was dissolved and Alistaire found his government contract transferred to R.C.X., but with Excalibur's help, R.C.X.'s corrupt leadership was stopped. Alistaire stayed on to help the new regime look after the mutated Warpie children left in their charge.^[6]

Shortly afterwards, Black Air began its rise to power as a government agency. Black Air seized the Warpies for experimentation, and struck a deal with the London Hellfire Club to arrange a coup. Deciding Alistaire knew too much, they targeted him for assassination and he fled to the U.S. He contacted Excalibur from the X-Mansion, and returned to the U.K. under their protection. Using the information he provided, Excalibur thwarted both Black Air and the Hellfire Club.^[7]

Alistaire was asked by the British government to reorganize all of the U.K.'s disparate government organizations handling paranormal affairs into a single Department under his leadership.^[8]

Sometime later, Alistaire discovered an imminent extra-dimensional invasion from Martian colonists. Reasoning that MI-6 had greater resources than the Department when it came to defend England from this threat, Alistaire decided to dissolve the Department and transferred to MI-6, hoping to incorporate the "weird happenings" under MI-6's banner. He neglected to tell Pete Wisdom the reason behind the dissolution, though, and Wisdom felt betrayed and abandoned by Stuart. Wisdom then successfully lobbied Mortimer Grimsdale, chief of the UK's Joint Intelligence Committee, to let him assemble his own agency to continue independently investigating "weird happenings". Grimsdale gave Wisdom his mandate, creating MI13. This sad twist prevented Alistaire from properly defending against the Martian threat, because at MI-6 he no longer had authority to investigate such things, nor could he tell Wisdom why he left to repair their relationship, because MI-6's hush mandates prevented him from sharing intelligence like that with other agencies.^[9]

Alistaire's cursed body is mutable, regularly changing appearance and extremely elastic; he has learned to exploit this, using the curse to analyze and manipulate magical energies on contact.

He is a scientific genius, mathematician and engineer, and well-read in philosophy, mythology and archeology. Before his sister's death, the two had an almost telepathic link, and he could sense when she was in distress.

• Alistaire Stuart is named after the Doctor Who character Brigadier Alistair Gordon Lethbridge-Stewart, also known as "the Brigadier", and is sometimes called "Stewart" himself.^[1]