Paul was jealous of his brother and resented the fact that Travis left the Horizon to join Starfleet and that Travis was not around when their father died. Paul 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 if the ship was attacked again in order to avoid bloodshed. However Travis, without Paul's knowledge, upgraded the weapons system. When the pirates did return they also demanded that the crew abandon the ship, the crew's home, despite negotiations on Paul's part. Paul decided to fight for Horizon and after having Travis bring the modifications online, Horizon was able to easily fight off the pirates. 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.