These are just the premades that we have openings for and want soon, not the exhaustive list of premades that one can take. Please see the premades list for the ones that are taken, the ones that are not on that list are available. Otherwise, onto the specific wants.
Caleb's sister is in play, and he also has plotting opportunities with the other vampires on the site, and our Morgyn is not against Cagyn, though the longer-lasting of the Calebs we had was dating Morgyn's goth twin brother, Ezio.
Mortimer and Bella Goth
Our Cassandra Goth would like her family members played as well. Bella is also a very iconic part of Sims lore, so we would certain do well having her on-site. Cassandra and Alexander have both been aged up.
A quick note, even if you have not seen these Sims in play before, you're still welcome to take them; all premade Sims act differently between players' games, so all you really need is to know their traits and interpret them how you will into the personality that makes sense to you. There's no real right or wrong way of playing a premade, so don't be afraid to give one a shot c: they're not quite like canons.