Re: Figured it out! Post your STID theories here
Vis-a-vis this point:
As for who Harrison is, perhaps it's a set-up for the next movie, to have Khan at the end the way that they teased the Joker at the end of Batman Begins.
I could see a possible introduction of Khan at the end with the plot I described. Capt April's Enterprise discovered the Botany Bay and quarantined the refugees. Knowing what it was, April took advantage of the advanced genetics and did some research of his own to produce his son: the genetically-superior John Harrison April ("I'm better at everything."). Khan and his crew are kept in stasis, with the plan to eventually release them and defeat the Klingon Empire completely... or possible overthrow the Federation.
I do agree that I can see a Joker-like teaser at the end of this film, as you describe it.