While all this was transpiring on Earth-6799, the cosmic entities known as Lord Chaos and Master Order psionically peered into the parallel-universe of Earth-030803. More specifically; they peered at that universe's counterpart of the world-killing sociopath known as Thanos the Mad Titan.
"He gets ever closer," said the former, unintentionally belaboring the obvious: "And, when he finds out I am not of feminine abstraction, like my counterpart, he will throw what the Terrans call a 'hissy fit!' "
"However did he get hold of a Qwardian power ring and a Mother Box, anyway?" asked Master Order.
"Oh, some Weaponeer, working as a mercenary for Darkseid of Apokolips, was on a gun-running trip to the Intergang of Earth-199098. When, suddenly, his boom tube was diverted to that alternate Marvel Universe by a wormhole that opened up near the Saturnian moon of Titan!"
"We must stop Thanos _before_ he gets here," declared Master Order.
"How? The Fantastic Four might be able to stop him. But, they are busy rescuing the Lindenbrook Expedition from the Mole Man! And, interrupting that would prove overly chaotic to the True Watchers of this universe."
"What about the Spider-man of that self-same particular altverse?" suggested Master Order: "He has proven himself brave, tenacious, and responsible. And, his fighting style is so unpredictable that it drives more physically powerful foes almost literally crazy!"
"Yet, was he not consumed by his ex-girlfriend? After being left stranded in a shrunken state by his jealous symbiotic costume?"
"We can see to his rescue. At the hands of someone who can give him an edge in fighting the cosmically powerful Thanos. The former Green Lantern known as...Donna Parker.* "
"His widowed great-aunt?" exclaimed Lord Chaos: "But, she is nearly a hundred Earth years-old!"
"Then, we will send someone back in time to recruit the help of her past self. Someone who has proven himself capable of traversing interdimensional barriers."
In less time than it takes to tell, the In-Betweener (personal servant of the two abstract entities) was conversing with that individual on a barren planetoid. An individual who was an amnesiac Terran superhuman from yet another alternate multiverse. An individual who wore a red costume high-lighted with yellow lightning bolts. And, who--up to now--had been exploring his adopted universe in the company of one of its self-proclaimed Elders; the Runner.
This mysterious individual was known only as...Fastforward, the Un-buried Alien. And, when the In-Betweener had explained the situation, the former had replied that he would be glad to help. Except for two problems.
"How am I going to visit this parallel-Earth without knowing its precise chronospatial co-ordinates? Let alone, without something to augment the kinetic energy I'll require?"
"That's where I come in!" exclaimed a new voice, with child-like glee.
"Who said that?" demanded the Un-buried Alien, looking all around.
Whereupon, a short green-skinned humanoid suddenly materialized between the two taller beings (with a popping sound that would have been inaudible in the normal environs of space).
"Me! Bum-bum-BUUUUUUUUM! The Impossible Man."
Five seconds later, the aforementioned humanoid shapeshifted into a green-and-purple treadmill. With Fastforward promptly hopping on to "his" back, and beginning to run at an eye-blurring speed. A speed that subsequently--and incredibly--only served to increase, from nanosecond to nanosecond!
Then, with another paradoxical "pop," they were gone.
Master Order and Lord Chaos were last seen meddling in Spidey's affairs in MARVEL TWO-IN-ONE ANNUAL #2 (1977).
Fastforward (alias "Buried Alien") was a Silver Age Flash pastiche who debuted in QUASAR (v.1) #17 (Dec. 1990).
And, the Impossible Man? He's sort of what the love-child of Mr. Mxyzptlk and the Martian Manhunter would be like if raised by G'nort G'neesmacher (instead of regular wolves).