This is my first post here, and I just want to say...
Luke's father Robert is Q.
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Q is Robert Sullivan
I'm surprised that I haven't seen anyone else propose this theory.
Robert's concept art looks like it was made to match Q's official art: his hair color is the same as Q's, his shirt has a large collar reminiscent of Q's trench coat, and his facial features even match the contours of Q's mask (most notably the cheeks).
Possible story: Robert could feel that he was about to spontaneously combust (see Q's Total Destruction), so he started yelling about a bomb to clear out the mall and avoid hurting anyone in the explosion. G sensed Robert's immense discharge of Earth energy and warped in to rescue him, turning him into a cyborg to save his life. ("Robert" even sounds like "robot" in Japanese!) G figured that someone who so strongly resonates with Earth's natural energy would be a good ally/weapon to have in preventing the apocalypse, so he befriended the now-amnesiac Robert and took him under his wing, teaching him how to control his powers. G uses his powers to telepathically communicate with (and sometimes commandeer) Q, hence Q's 3rd Strike win quotes.
Luke's moveset appears to contain several references to Q in order to make the familial connection apparent:
Q's High Speed Barrage looks like a sloppy, projectile-free version of Luke's Rock Smasher/Vulcan Blast:
Luke's super is three identical hooks followed by multiple body blows followed by one final hook, and Q's is three identical hooks followed by a single body blow followed by one final hook:
Robert and Q are both often depicted with their backs turned to the camera:
The scene of people running away scared from Robert is also incredibly reminiscent of Q's intro animation:
So, yeah, this is obviously all just a theory, but it's one I feel very strongly about.