Caleb Vatore is in every one of my saves. I have half a town that are descended from him (I was looking at group of three blond vampire siblings last night and it occurred to me that they're vampires due to great-grandfather Caleb on one side and blond due to grandfather Lucas Munch on the other, because apparently those genes are STRONG).
I started a vampire in a new save and sent him over to Caleb and Lilith's house with the thought that whichever one of them he liked better on his own would be voted in as spouse, and went scrolling around the town looking for collectibles and plants. By the time I got back my sim had learned all of both Caleb and Lilith's traits and was friends with Lilith, but good friends and romantic interests with Caleb. So maybe it's just that Caleb wants to be in MY game. ;)