"Love is as real as a force as gravity - you should try it sometimes" - Aurelion Sol
Just why does
give of the feel like he really knows what he is talking about? Could it be... that he really has been in love before?
And that would explain something in his backstory that never made much sense for me: how did the Targonians trick a comisc, star-creating dragon? In the version we have, they made a fancy crown and Sol, the vain fuck that he is, immedeatly decides "I'm gonna rock that look", put it on and is suddenly enslaved.
However, where did the Targonians get the knownledge of how to bind him? And why did he accept the crown even if the primitive and "crude" magic as he calls it would have been detectable? That would literally go against all logic... unless, the great remover of all logic and rationality was involved: love.
Let's just assume that Aurelion Sol fell in love with a Targonian, who finally either betrayed him or was forced to betray him in the end. Now the story makes a lot more sense, right? He didn't just put on the crown out of vanity, he put it on because he truly trusted the person or being that he was in love with. However, he'd rather look like a vain moron than to be reminded of this betrayal, so instead we have the version we all know as a main-lore that leaves out details such as this.
And now: even more speculation: Who was the targonian entity that Sol was in love with? Pantheon surely not, the Protector seems also unlikely, and apart from that we only know of the aspect of the sun and the aspect of the moon. If he had a relation to one of those he'd surely have a specific taunt for Leona or Diana, so that is also unlikely. He has taunts for them, but none that would suggest something like that.
However, what if we were talking about a "fallen" Targonian here? Like, a cosmic entity that was "banished" in some way after it had been forced to betray Aurelion or opposed the plan to enslave him?
Thinking about it we only have one "fallen star" in our mass of champions, or at least someone who might fit the description: 
He even has a taunt for her: "Twinkle, twinkle, little star, do you wonder what you are?", implying that he knows something about her that she does not. But how would Soraka not know about something as once having dated a gigantic space dragon? Well, as I see it a memory-loss is not very unlikely when she was really "banished" as a targonian aspect and "downgraded" from a cosmic entity into whatever she is know. That would also explain why Soraka had a magical "leash" that would prevent her from using her magic to harm others: the moment she used the full extend of her powers to get rid of Warwick's men she got her goat hooves... (I hope that still is the canon version of the lore). It would make sense if she was banished and sealed, mostly because she poses a danger to the other targonians.
On another note I am kind of fascinated that a gigantic entity like Aurelion Sol can even flal in love. I wonder what's his type when it comes to partners tho, apart from "don't be a targonian"... or would he even look at a being as long as it was less than a cosmic god? All very interesting questions ^^