Their energy bar will deplete and they’ll be close to death in no time. Your sim will need to avoid the sunlight and not stand there for too long. Once that’s done, in three days you’ll have a vampire sim to play as! This will secure that they won’t turn you down when you then select, “Ask to Turn.” If you do so and they agree to it (they might not have enough vampire points to do it), your sim will get bitten and the ritual begins.
You’re going to want to work up your relationship with them (either friendship or romantically), so do your thing until you’re at Good Friends level. You’re going to first want to have your sim meet a vampire. If you want to do this the harder way, though. It’s a lot easier to just make a vampire, let me tell you that right now. You can make them from scratch into these night stalkers, or you can organically turn them from within the game. The Sims 4’s latest game pack will let your sims embark on a life of immortality with the new Vampires. How to Turn into a Vampire – The Sims 4: Vampires Game Pack
