From The TV IV
Susan is the granddaughter of the Time Lord we know simply as The Doctor. She is extremely brilliant: a genius. Although she is not fearless by any means, she can be quite brave should the need arise.
She is driven by a fundamental dichotomy: on the one hand she wants to settle down, to have a place to call home; and on the other hand she has a love of exploration and her grandfather.
During her time in London during 1963, she went by the name Susan Foreman. However, the name Foreman was simply an alias to help her fit in. It was borrowed from the name of the junkyard where the TARDIS stayed during that visit.
She and her grandfather travelled with Ian Chesterton and Barbara Wright for some time, becoming quite fond of them. However, they had travelled space and time a great deal before ever meeting Ian and Barbara.
She finally got her chance to settle down in 22nd century London. Knowing that she would never voluntarily leave him, her grandfather locked her out of the TARDIS, explained his motives, and left her to her new life with the young man she had fallen in love with, David Campbell.
- Susan claims to have coined the acronym TARDIS in the episode An Unearthly Child.
- She exhibits telepathic powers in certain circumstances, such as during her time on Sensesphere.