Their enemy? Good point. But as the saying goes, "Keep your friends close and your enemies closer".
Interesting that it would be Aria. Adagio I could see as she had the most in common with Sunset, and Sonata certainly seems amiable enough, but Aria seems like she would have been too rough and standoffish.
It's okay, Sunset. Just tell Twilight & she will be okay with it.
Oh, who cares how many were in the race? the point is Twilight came out the winner!
i see trouble in the future. plus you should tell twi she deserves to know
Oh here we go o:
Well, you might want to bring it up, Sunset. Only a matter of time and it will blow us bad if not brought out healthily.
To answer your question: probably by saying the words "I was dating a siren".
Honestly, if you think about it, not that hard to wrap your mind around. Both Sunset and the sirens fell from a high position of ultimate power, and then had to build from the pieces left behind. Where sunset had friends to fall back on, the sirens had no one; so it only stood to reason someone who's been there before would be there for them. In doing so, keeping close can sometimes lead to more. Sure, it could be hard to accept at first, but if they can accept one reformed magical entity bent on world domination, no sense it can never happen again