Through the eyes of Tidus, the Al Bhed left a threatening first impression when he first met them at the Submerged Ruins/Baaj Temple. Although Rikku helped him fight off the fiend, Tidus quickly found himself at gunpoint without any understanding of what was going on due to the language barrier as the Al Bhed were conversing in Al Bhed (and for the first playthrough of the game, the player wouldn’t know what they were saying either because the subtitles weren’t translated without obtaining any Al Bhed Primers).
Although Rikku was friendly towards Tidus and was the only one who tried to communicate with him after her crewmates brought him to the Salvage Ship, the Al Bhed were made to be antagonistic during the first half of Final Fantasy X. During the Blitzball tournament at Luca, Yuna was kidnapped by the Al Bhed Psyches to force the Besaid Aurochs to lose the game. When Tidus and company met Issaru and his brothers at Djose Temple, although they did not know that the Al Bhed were behind it at the time, Maroda, Issaru's brother and guardian, told Tidus about summoners disappearing out of nowhere. While crossing the Moonflow, the Al Bhed tried to kidnap Yuna again. The Al Bhed tried to kidnap Yuna once more at Lake Macalania. The series of summoners kidnapping, without proper explanations, made the Al Bhed enemies of Yevon that purposely got in the way of the summoners’ pilgrimage.
It was not until the player reached the Al Bhed Home that the reasoning behind the Al Bhed's extreme actions was clear, and that they were not the villains they were made out to be.
All the Al Bhed wanted was for Sin to be ultimately destroyed and to obtain lasting peace for Spira. They felt that Yevon's method was not good enough, because it required the sacrifice of summoners just to chase Sin away for a short amount of time before the cycle repeats itself. The Al Bhed kidnapped the summoners to protect them, so that they do not sacrifice themselves needlessly for a temporary solution to Spira's problems. The Al Bhed also didn't think twice about protecting the summoners from the Guado and the fiends when Home was invaded. They were willing to put their lives on the line for the summoners.
From Operation Mi'ihen, one could see that the Al Bhed shared the same goals with the rest of Spira. Although the operation ended in failure, the Al Bhed were willing to work with the Yevonites and put themselves on the frontline to battle Sin with machina weapons. Perhaps the Al Bhed felt that the use of powerful machina might be the ultimate solution in permanently eliminating Sin from Spira at the time.
The Al Bhed might have come off as strange and extreme at times, but they had the best interest of Spira in mind. They wanted to rid Spira of Sin in as few deaths and sacrifices as possible.