Well... that was totally awesome and crazy, wasn't it?
On The Vampire Diaries Season 5 Episode 3, viewers were introduced to Janina Gavankar as Qetsiyah, a self-described paranoid/controlling/crazy witch who resurfaced outside Mystic Falls to settle an ancient grudge with Silas.
What kind of grudge?
The kind where he pretends to be in love with you 2,000 years ago... just to convince you to make an immortality potion... only he steals that potion on your wedding day and takes it with his actual true love, who happens to be a doppleganger that looks just like Elena Gilbert.
So you create a cure for this immortality potion, feed it to the doppleganger, rip her heart out and trap Silas in a tomb with the cure in the hope that he'll take it and be dead once and for all.
You know. Basic scorned witch stuff.