When Last Christmas opened with Santa and two of his elves on Clara's roof (nice house by the way!), at first she didn't want to believe it was really Santa on her roof. After some rather condescending 'truths' were revealed by the elves and Santa himself, though, the familiar sound of the TARDIS was heard along with the craft itself materialising before Clara's eyes. The Doctor then tells Clara to not to say a word and to simply go in the TARDIS. After a few seconds of wondering if it was really the Doctor, with confirmation from him as well, she does exactly what he asks of her. While there is no on screen confirmation regarding how much time has passed for the characters between Death in Heaven and the Christmas Special, viewers must assume it's been at least a few months, if not more. For Clara to do exactly what he asks of her is astounding. Not even a casual question of 'Where have you been?', 'How are you doing' - nope, none of that at all. It shows the amount of respect and trust she must have in this man to happily do what he says, no questions asked.