Two episodes into 'Clara Prime's' tenure in the TARDIS and we got our first look at how how good Jenna Coleman could be. With the Doctor unable to satisfy the hunger of the god sun, she rushes to his aid and holds up the leaf that represents her own personal history, the history of her mother and father, the most important leaf in history. It shows her as as a compassionate hero, willing to throw herself into danger. It is a trait we would see time and time again, most importantly jumping into the Doctor's own timestream to save him in The Name Of The Doctor. Arguably that moment - her most important moment - is set up here and audiences witnessed an emotional, nuanced performance from Jenna Coleman that would make her one of the most important companions in the history of Doctor Who.