No, your body is contstantly renewing and filtering your blood.
would his blood still be in mine forever though
How did you mix the blood in the first place?
How would that make you related? LOL, that doesnt even make sense.
How old are you? his blood staying in your body make you related to him, thats crazy 5 year old games, but for being a hiv risk it depends of how you mixed blood with your friend, but it can be a risk depending of the circunstances.