On the Dead Games Society podcast #38 we talk a little about the tragic romance that is Strahd Von Zarovich's origin story.
In the original AD&D Ravenloft adventure from 1983, known among collectors as "I6," we are introduced to a most cunning Vampire Lord that harries the Player Characters throughout their journeys within the Transylvania-like realm of Barovia. The villagers name him as "The Devil Strahd," and that he lives in the mysterious castle that perches above the village like a waiting vulture. This mysterious Strahd expertly performs guerilla-like attacks on the PCs as they travel and camp at night, striking only once or twice before fading back into the shadows. Eventually the PC's may explore Castle Ravenloft and find Strahd's personal journal, wherein he describes in his own hand (and point of view) how he came to become obsessed with his younger brother's fiance as well as his own creeping mortality, and made a pact with some dark entity to the blood-drinking master of Ravenloft.
"With words she called me “brother,” but when I looked into her eyes they reflected another name – “death.” It was the death of the aged that she saw in me. She loved her youth and enjoyed it. But I had squandered mine. The death she saw in me turned her from me. And so I came to hate death, my death. My hate is very strong: I would not be called “death” so soon. I made a pact with Vol, a pact of Blood. On the day of the wedding, I killed Sergei, my brother. My pact was sealed with his blood, his…divinity.
I found Taryana weeping in the garden east of the Chapel. She fled from me. She would not let me explain, and a great anger swelled within me. She had to understand the pact I made for her! I pursued her. Finally, in despair, she flung herself from the walls of Ravenloft and I watched everything I ever wanted fall from my grasp forever."
-Tome of Strahd
During the adventure, the PCs are tasked with protecting Ireena Kolyana from Strahd's affections (who he sees as the reincarnation of Tatyana). He constantly tries to separate her from the PCs and whisk her away to Castle Ravenloft to woo her into loving him. However he thinks the best way to do that is to charm a PC into attacking her and then swooping in to destroy that PC in front of her. He's not a super lovey-dovey dude. Based on that diary passage above, I don't think the Strahd fall from grace is about love so much as obsession with her youthfulness and rebelling against his encroaching mortality. When Strahd says that he "Loves" Tatyana (Ireena), its really more about his obsession with her youthfulness and carefree life. Love is reciprocal and pleasant, Obsession is more one-sided and lustful. I think it could be argued that obsession may be a stronger emotion than Love, and I don't think Love is really a power that would create vampires, after all. So when Strahd is chasing after the PCs in I6 and trying to capture Ireena, I think he subconsciously understands this lost cause, and knows that she will never actually love him, no matter how much he whines about it. He doesn't expect to actually get her. He simply desires a justification to feel persecuted again, to be perceived as a martyr as much as possible. Of course, once he achieves that goal of being rejected and again proving the injustice of "love", he'll he'll happily rip the rest of the party to shreds. Happy Valentine's!
So that's a bit of my take on Strahd's personality, but developing your own understanding of Strahd's motivation is key to playing him as interestingly as possible if you dare take your players through the original I6: Ravenloft.
You can listen to me ramble on and on about how much I love Ravenloft (with tangential references to Valentines Day) on the DGS Podcast #38!