Thel, like all Sangheili, is keen to do things in an honorable manner, though he is more flexible when it comes to equipment, weapons, and vehicles. His hatred of the Jiralhanae doesn't seem to be as strong or destructive as that of other Sangheili; one example of this is when the Arbiter tried to reason with Tartarus in Installation 05's Control Room. He is shown to be true to his title "Arbiter" as he often tries to negotiate with some of his other enemies (Yanme'e, for example) and will only kill when forced to do so. He has deep respect for his fellow Sangheili and a grudging respect for the humans, specifically John-117 and Sergeant Johnson.

Despite being a former enemy of humanity, Thel has shown a willingness to fight alongside them toward a common goal. Even before peace was established, Thel was willing to work with Avery Johnson to stop Tartarus. Johnson's aid in the fight with Tartarus and the fight he put against him earlier may have earned Vadam's respect as he seemed to respect Johnson in their later encounters. He also showed sorrow at Johnson's death, and said that even beyond death, the Sergeant still guided them. He was also willing to fight side by side and back to back with the Master Chief, someone he once considered a great enemy. Thel also respected humanity enough to be present at a memorial to everyone who fell in the war. While he respected the humans he was wary of their intent and likely had his own reason for having Evan Phillips visiting Sanghelios. 

Although he often conducted himself with honour and a measure of tolerance towards others, he was not beyond pride and impatience, and would sometimes act dismissively or condescendingly to people like Catherine Halsey or Spartan Locke. Those who did not know him well frequently thought him stubborn and willful.