Just like Havok, I'll give you three hints. Hint one: he IS a Summers. Hint two: he is the current emperor of the Shi'ar empire. Hint three: he can absorb energy and can release it as a blast from either his eyes or hands.
His name is Gabriel Summers, aka Vulcan or emperor Vulcan.I'm not sure if he is the eldest or the youngest, but he is Cyclops and Havok's brother. He was once a part of the X-Men. His backstory is sad. Apparently, he was "ripped" from his mother's womb and was grown from infancy to adulthood in a machine and the void makes him realize that while he may look grown up, he is basically a child, having not grown up the way he should have. Never knowing parental love, he grew to be ruthless. If anyone knows more on him, please comment or message me and correct any of my misinformation as I don't want anyone to think that all of this is correct.