In The Originals S01E10 'The Casket Girls', Why did Timothy aka Tim die? Tim and Davina both were poisoned by Klaus and were dieing. Rebekah told Klaus that they used vampire blood too for healing them but they died, Davina survived due to th protection spell. Tim died with vampire blood in him so isn't he supposed to come back to life as a vampire? Why didn't he turn and just died?
It was established in this episode that there are some poisons that cannot be cured by vampire blood, as Josh and Rebekah fed both Davina and Tim their blood with no success a that is why Tim didn't Turn. According to Klaus, he chose this poison for that very reason.
This explanation is mentioned in this page: http://vampirediaries.wikia.com/wiki/The_Casket_Girls