Alex Campbell (Restoration of the Daleks)

Alex Campbell was a companion of the Eighth Doctor.

An alternative version of the Doctor's great-grandson, Alex was taken from his universe by the Dalek Time Strategist and joined the Doctor in his adventures, travelling with him and Cass Fermazzi after Bliss vanished from their memory.

Early life
Whilst Alex was mostly human, he was also part-Time Lord due to him being the Doctor's great-grandson. (AUDIO: Meanwhile, Elsewhere) The Doctor once gave him a temporal interocitor. (AUDIO: Previously, Next Time)

The Dalek Time Strategist found and captured Alex during his sojourns through the multiverse and attempted to use him to manipulate the Eighth Doctor into ensuring the destruction of Gallifrey and end the Last Great Time War. The Doctor refused and revived him from a cryogenic casket after thwarting the Strategist. (AUDIO: Restoration of the Daleks)

Travels in the TARDIS
Alex joined the Doctor in the TARDIS, but the Doctor kept him unaware that the version of him from his universe was dead, (AUDIO: Meanwhile, Elsewhere) having been killed by the Daleks. (AUDIO: To the Death)

Upon arriving on Shimmer, Alex and the Doctor met a future Alex and Cass Fermazzi, who confirmed the Doctor's belief that there was a hyperstatic temporal incursion. Alex and the Doctor travelled from Shimmer to three other planets to close the resulting portals, with Alex meeting Cass for the first time from her perspective whilst on Hervandel. Upon arriving on the EC-141, he destroyed the ship's engine before going back in time with Cass and meeting his past self on Shimmer; once the situation was resolved, Cass joined Alex and the Doctor in the TARDIS. (AUDIO: Meanwhile, Elsewhere)

Alex, the Doctor and Cass travelled to Station Twilight and descended to examine the Vespertine, where they found Hudson Sage living inside a time lock. Alex and Cass used his memory recorder to look back in time and learnt that the Doctor had been on the ship with Bliss, a companion that the Doctor had no memory of. Following the Vespertine's destruction, Alex told the Doctor that he believed that the Doctor's timeline had been changed, but the Doctor theorised that the timelines of everybody outside of Hudson's time lock had been changed. (AUDIO: Vespertine)

When the TARDIS was unable to fix onto the timeline and the Doctor caused it to crash-land on an uninhabited planet, they found a factory and Alex and Cass distracted the Daleks whilst the Doctor went to cause their Battle TARDIS to implode. However, the Daleks exploded it and sent Alex, the Doctor and Cass a year back in time where they prevented the Daleks from setting up their factory by shutting down the Battle TARDIS. The inhabitants of the planet, created by the explosion, were erased from time and Cass vanished, although Alex and the Doctor managed to remember her and swore to find her. (AUDIO: Previously, Next Time)

Personality
Unlike his other self, Alex was enthusiastic about travelling in the TARDIS. He was flirtatious, had some knowledge of temporal mechanics (AUDIO: Meanwhile, Elsewhere) and did not believe in ghosts. (AUDIO: Previously, Next Time)

He openly flirted with Cass Fermazzi, suggested he would appreciate an opportunity with her younger brother, and even engaged flirtatiously with himself, displaced somewhat in time. (AUDIO: Meanwhile, Elsewhere)