Bill healed the bite marks from Callum’s neck in the 80’s before the Great Revelation. Probably because he didn’t want humans to be aware of vampires. We can assume all vampires concealed any trace of their feedings or killings.
Now my question is, if Bill only wanted to protect Sookie, why didn’t he heal those bite marks? More so when there was a serial killer on the loose, killing fangbangers.
Many have explained this as Bill wanting to alienate Sookie from her friends and family or Bill wanting to show his ‘ownership’. If that was the case, he took an awful risk with Sookie’s life and would have been directly responsible for her death.