Paul was jealous of his brother and resented the fact the he left the Horizon to join Starfleet and that he was not around when their father died. He also believed Travis to be their mother's favorite, further alienating the brothers. Paul also believed that if Travis had stayed on the Horizon, then Travis would have become captain upon their father's death instead of him.
While visiting the Horizon in early 2153, Travis and Paul came into conflict on how to run the ship. Travis tried to upgrade several systems on the Horizon, but Paul took exception to this and believed that his brother was trying to embarrass him in front of his crew.
When the Horizon was subsequently attacked by pirates, Paul decided to give up the cargo and the ship if the ship was attacked again in order to avoid bloodshed. However, Travis, without Paul's knowledge, upgraded the weapons system and, after convincing Paul to accept the changes, the Horizon was able to easily fight off the pirates, though Paul allowed them to leave so they could give their compatriots an account of the incident and warn them that attacking ECS ships was not a good idea.