Lorian

"Only in the Expanse can I have a son who's nearly three times my age."
 * - Charles Tucker III

Lorian was the commander of the from an alternate timeline, in which Enterprise was thrown back in time from the year 2154 to 2037. When Enterprise attempted to use a subspace corridor to travel to a rendezvous with Degra as part of their mission to save Earth from annihilation by the Xindi, their damaged impulse manifold destabilized the corridor, causing it to shift in time and transport Enterprise into the past. Eventually realizing that the corridor only permitted travel one-way, and that there was no way to return to their own time, Enterprise became a generational ship, whose crew's descendants were given the mission of preventing the first Xindi attack on Earth, thereby saving seven million lives.

Lorian was the son of Vulcan science officer T'Pol and Human chief engineer Charles Tucker III, a conception made possible after Doctor Phlox found a way of combining the Vulcan and Human genomes. Lorian was influenced by both of his parents, and over his lifetime, he was able to balance emotion and logic.

Lorian's father died when he was fourteen, but Lorian taught himself engineering by reading his father's old logs. While Captain Jonathan Archer was on his deathbed, Lorian promised the captain he would continue his mission to stop the Xindi probe from attacking Earth. Upon Archer's death, Lorian became the captain of Enterprise.

However, Lorian was unable to stop the Xindi probe from reaching Earth when it launched in March of 2153. He had planned on ramming the probe with Enterprise, but hesitated, unable to give an order that would kill his entire crew. The moment passed, and by the time he had made his decision, the probe was gone, en route to Earth. With no other alternatives, he was forced to wait until Enterprise once again entered the Delphic Expanse in search of the Xindi superweapon, in order to prevent it from entering the subspace corridor that would send it on its fateful journey through time.

In February of 2154, Lorian took Enterprise to meet the present version of the vessel just before it entered the subspace corridor. However, Lorian needed to provide an alternate way for the ship to reach its rendezvous at the Xindi Council, so he provided the present-Enterprise with Haradin schematics that would allow them to modify their plasma injectors and increase speed to warp 6.9 for brief times. However, Archer rejected Lorian's plan on a recommendation from the elder T'Pol, who demonstrated that there was a risk that if the ship exceeded warp 5.6, the injectors would overload and destroy the vessel.

T'Pol's alternative was reconfiguring the impulse manifold so it would not destabilize the corridor and send the ship back in time, but Lorian was not convinced it would work. He stole the plasma injectors of the present-Enterprise so that his ship could make the rendezvous (as his own injectors were too old), but Archer talked him into assisting with T'Pol's plan. With Lorian's ship's help, Archer's Enterprise made it past a group of Kovaalan ships which were between them and the entrance of the corridor. Lorian attacked the Kovaalan ships and kept them busy, allowing Archer's Enterprise to safely enter the corridor and successfully rendezvous with Degra, who proceeded to escort Enterprise to the Xindi Council planet.

Lorian's ultimate fate, as well as the fate of the rest of his crew, remained unknown. It was speculated by Archer and T'Pol that his ship was destroyed, was able to escape, or even that, due to both crews' success in changing the timeline, his ship might have been erased from history. 

Lorian ロリアン