Well here's what I was thinking Russell's arrival sort of shakes things up for everyone and more specifically The Countess, despite her initial curiosity as to who the newest guest of the Cortez is I have a feeling once she realizes who he is and the legacy, influence, and status he has among vampires Elizabeth has always been thought of as the queen of her domain but to be a literal queen doesn't seem like something she'd pass up on and try to seduce him, but perhaps in her pursuits she sees Russell's eyes more on Donovan than her so she backs off and has him do the work instead.
In the process of getting the older man to fall for him it backfires Russell could use what he learns about him against her like how she'll never truly love him and will throw him out when she finds someone else.
People often see his as a victim anyway and thinks the loyalty he gives her she doesn't deserve, perhaps Russell could prey on those weak spots between them along with Donovan's desires for love, happiness and even his dreams of being an actor to win him over because he doesn't want the Countess at all but her lover and the unconditional love and loyalty he has for her to belong to him as he plans to get back to his goals of ensuring the supremacy of vampires over humans and lures the new object of his affection away with him.
To make a long story short when it comes down to it Donovan's just as depicted as he was in the series however with my twist he didn't die either or at least not long anyway. As a result of the residue of his ashes lingering into the blood of the deceased Queenie her powerful bloodline was so powerful it brought back the deceased vampire. Finding himself in Miami without his beloved creator or overbearing mother Donovan drifted into a strip club where he was hired on the spot because of his looks and knowledge of arts. Saving up every bit of cash he received it wasn't long before Donovan left it behind lavishing himself back into the life of luxury he's accustomed too, but in order to keep it up he's became a bit of a notorious and well respected con man known as Nathaniel Lincoln and doing well for himself owning to residences in Miami and New York. I drew inspiration from Matt's other characters Neal from White Collar and Ken from Magic Mike to construct what he's been up too. Despite doing well though it does get lonely not having someone to share this hard knock yet luxurious life with but knows it's for the best but keeps his mother and The Countess with him as he keeps going, there's also the added bonus with the powerful witch blood within him now infused with his own vampiric blood there's a possibile untapped power just waiting to be unleashed.
Of course stories that take place as if he didn't die or before his death at the Cortez are fine too, just depends on what the person I'm writing with wants to do and I must say the idea of Russell at the Hotel seems like it'd be very fun so let me know what you'd prefer to do and we can come up with an idea from there!