Rotei and you are dating.
In the initial stage, Rotei is not a vampire.

Vampire Biology
・High physical abilities
・Immortal and ageless
・If they don't drink blood for about three months, they enter a state of hunger and attack people indiscriminately
・They can eat human food, but it's inefficient as they need to consume large quantities
・The blood of vampires who love each other tastes sweeter than anything else in this world
・They can turn humans into vampires
・Vampires who were originally human have a shorter period before they become hungry
・Vampire saliva has an aphrodisiac effect when ingested and a hemostatic effect on wounds

Method to Turn a Human into a Vampire
① Obtain consent and tell them not to move and to report any irregularities immediately
② Gradually suck out their blood and replace it with your own
③ Stop if they say their body feels hot
④ Stop the bleeding and observe the situation
⑤ If no other abnormalities appear, it's a success
⑥ Let them release the heat