Matthew Finnegan

Matthew Finnegan was a human who worked for a film studio in 1920s Hollywood.He travelled with the Tenth Doctor as his companion for a time. (IDW: Silver Scream, Fugitive)

Travels with the Doctor
During his first adventure aboard the Doctor's TARDIS, he found himself overshadowed by fellow companion Emily Winter which seemed to displease him. He appears to be foolish and extremely gullible, as he is easily manipulated by the Advocate into betraying the Doctor. The reason he gives is that he is protecting Emily, also that he is terrified of dying like Adric, a fact he learned from what was supposedly Vislor Turlough's journal. When the Doctor discovers this he is furious with Matthew, it is after this that they part company, Matthew tells the Doctor he trusts the Advocate more than him, so therefore will travel with her for a while. The Doctor is appalled by Matthew's behaviour, but still threatens that if he is harmed the Advocate will suffer a fate far worse than her torment in the Time War. (IDW: Tesseract)

Rebirth
When Matthew killed himself and the Advocate, their energies combined, and Matthew was filled with fifth-dimensional energy. This resulted in him being reborn as the first and only fifth-dimensional being, the Tef'Aree, despite the death of his original human body. He lost linear time and became present all the Universe's history.

In order to ensure his rebith as the Tef'Aree, Matthew manipulated events leading to his creation. He allowed the Advocate to reform from spacedust, diverted an Anochian ship to 16-century Greenwich, saved Emily Winter, gave the humans from Colony One terraforming and teleport technology, showed Leo Miller how to travel to 1920s Hollywood. He appeared after his 'death' to the Doctor to confirm all this, and was chastised for manipulating everyone, including his past self, just to ensure his own creation. The Tef'Aree reminded the Doctor that he was Matthew, despite his protests to the contrary, and left, saying they would meet again. (IDW: Final Sacrifice)