I have both Nightlife and University Eps. In the instruction manuel it says watch out if your sim becomes close to a vampire as it might end up as one. I wanted to try this for a laugh my male sim is in a relationship (love) with a female vampire they have woohooed and everything, so how does he become one like her naturally (without cheating).
Also I wanted another to become an alien so I tried to get her to use the telescope constantly and still no joy how do I increase her chances.
And lastly what do the offspring of Vampires and Aliens look like? And does it make a difference if one is still a human?

To become a vampire, you have to accept an offer to 'bite neck' off a vampire. They should do it autonomously if they are friends, so to make it happen without cheating you just have to wait.
There is a very small chance of being abducted, and it only happens if you stargaze at night (I think it's between 7pm and 1am- is that right?) So to get abducted, you either have to stargaze at night until it happens, or cheat.
Vampire babies are normal skinned, they inherit their looks from their parents (the vampire skin is just like a body tattoo, and the red eyes like contact lenses). Alien babies inherit parent's genes too, so they can have any combination of the parent's eye colour, skin colour and features dependent on which traits are dominant. I've had babies with human eyes and skin but alien features, and babies that look human except for black eyes.

Thanks

Simsample, 7:00pm and 2:00 am

Evie, it sounded in your first post like you wanted a sim to become an alien. Any sim teen, adult or elder has a chance of being abducted. .05% with out hacks. Thats not 5% it is .05%! 1 out of 10000. But the abducted sim does not become one. A male adult sim with more than 3 days of his adult life remaining will in all likelyhood come home prenant by alien pollination techniques. The females do not get this "special" treatment! The teens and elders just get credit for the abduction, and the memory of it. It is beneficial for a teen to be abducted if they are going to college. Every one can gain extra aspiration points for multiple abductions. (At least the knowledge seekers can).

I wanted my sim to become a vampire, so i hooked him up with the countessa,and iit took a while but she finally bit him. Funny thing tho, he had a friend over and asked him what he wanted. he wanted to be a vampire. so i had my sim call the countessa and invite her over, well she walked right into the house came up the stairs and immediately made his friend a vampire. not one word to anyone ,dammest thing i ever saw. shortly after that she bit him when they were on a date.