There apparently is more to the Octavia and Vinyl Scratch story after their unlikely pairing. (Disclaimer: non-canon fanfic ahead!)
Octavia: "I was going to be first-chair cellist for the Royal Canterlot Symphony...how is this my life?"
DJ-Pon-3: "Don't worry everypony... I GOT THIS!"
At first it seemed that Pinkie Pie had single-hoofedly caused Octavia's fall from the Canterlot musical elite...
Pinkie Pie: "Yo, Octavia, I got a song request. Do you know how to play 'The Pony Pokey'?"
Octavia: "I mostly only know classical music, but I could give it a shot..."
Octavia: "My bow tie, my cello, my career, nooooooooo!"
Miraculously, Octavia and her cello survived the precipitous drop, her future prospects for Canterlot gigs, alas, did not...
...forcing Octavia to move to Ponyville, die her hair and mane, adopt country manners, and forge a new musical career as a fiddle player. She boarded with another musician, Vinyl Scratch, who went by stage name "DJ Pon-3." Despite their differences in personality and musical taste, the two became the fastest of friends. There are some things you can't share without ending up liking each other, and letting another pony eat the rest of your sandwich is one of them.
The devil went down to Ponyville... and made a bet with Octavia. Turns out he's a fiddle player too...
...The devil bowed his head because he knew that he'd been beat.
He laid that golden fiddle on the ground at Octavia's hooves.
Octavia said: "Devil just come on back if you ever want to try again.
"cause I told you once, you son of a gun, I'm the best there's ever been."
Octavia must have impressed a music agent attending the Nightmare Night celebration since she received a new gig to play at a Canterlot party and she didn't even have to sell her soul to do so!
Octavia's a pretty good fiddle player, in fact, she's the best, but the cello's always been her true passion... wait, who's that clone next to her?
Octavia and her band (the Royal Canterlot Symphony) once again became one of most sought-after acts in Equestria and she made enough bits to move back to Canterlot. Thus, reluctantly Octavia and Vinyl parted ways, ending their odd-couple fellowship... They still kept in touch, of course, because everypony likes happy endings.
What of her friend Vinyl Scratch? Well, after defeating Discord with her bass cannon, she was given the great honor of DJing at the wedding party of Shining Armor and Princess Cadence, and DJ Pon-3 even showed us her eyes, AH YEAH!
And the ponies lived happily ever after... until 4 a.m. in the morning, when the pegasus guards were called in to break up the party for disturbing the peace.