I am…The Watcher.
In your universe, Scott Summers is a mutant known as Cyclops. The brave and fearless leader of the X-Men. From him stem and his actions, many events that effect mutantkind have their origin with him. From him being Cable’s father, his relationships with Jean Grey and Emma Frost, his rivalry with Wolverine, his hounding by villains Mr. Sinister and Apocalypse, the creation of Utopia, his transformation into Dark Phoenix, the killing of Charles Xavier…the man with the ruby quartz visor is seemingly the catalyst.
When he was 12, Scott and his family were flying in a small plane across Alaska where they happened across a Shi’ar spacecraft. Though their father, Christopher, was an air force pilot he was in a light plane with no armaments or weapons. The alien craft fired, and the plane went down. In your universe Scott held his brother and parachuted to safety whilst his parents were kidnapped back to the Shi’ar Empire.
In this universe, the Shi’ar were not so forgiving. They opened fire on the small de Havilland plane and blew it apart in midair killing all aboard in ghastly fireball.
No Cyclops. No Havok. No Cable. No Stryfe. No Rachel Grey. No Hope Summers. No Nathan Summers. No Vulcan. No Corsair. The entire Summers line gone from this reality and their actions as well.
Charles Xavier focuses his energies upon Jean Grey, helping her earlier on to control and use her powers. He builds the X-Men around her. Warren Worthington aka Angel and Jean become an item in seemingly better more stable matching. But without Cyclops on their first mission, Magneto thoroughly defeats them and escapes from Cape Citadel with several nuclear warheads. The tide of anti-mutant sentiment rises quicker due to this debut loss.
How far reaching is the ripple of Scott Summers?