Suzi Palsson was the Chief Archivist and Librarian of Gadrell Major.
Her boyfriend for a while was Colm Oswyn. When he broke up with her, Suzi was distraught. Later, at a wedding where they were both guests, he got drunk on green dragon cocktails. After going outside, he slipped and fell into a bay. Suzi was the only witness and when he called out for help, she let him drown.
Later, when she met Shanstra, the Sensopath fed on Suzi's regret and pain from that decision. When they met Livewire, the feral child's hate for the invading Phractons was more appealing to Shanstra, who abandoned Suzi.
The Seventh Doctor took Suzi and Kelzen to the Pridka Dream Centre to track down Jirenal. He sent her to the Dreamguide to deal with her feelings about what she did to Colm. At first she became trapped, but was able to overcome her fears, then was freed by the Doctor. After defeating Shanstra, he took her back to Gadrell Major.
After Shanstra was killed, though, there were still militants amongst the Phractons who wanted to fight the humans. A shuttle explosion which killed Suzi Palsson and Darius Cheynor mollified them, as they blamed Cheynor for the death of their Commander on Gadrell Major. It also removed the last remnants of the Sensopath's influence. The Doctor explained this to Bernice Summerfield, saying that because it was part of history he could not interfere. (PROSE: Infinite Requiem)