(This is for the fanfiction "Crossover Together". Info may change from canon information)
Hoopa is a more selfish individual, and doesn't really try to associate himself with others unless either forced into it, or if he could find something to gain out of it. This does make him less compassionate, and mainly looking out for himself. The most evident moment of this was him chewing out Aladdin after they ended up teleported to Lugia's island.
Prior to the series, Hoope was trapped within a Djinn vessel by Heine Wittgenstein in Synapse. He managed to escape though after Aladdin accidentally released him, and ever since then he had gone into hiding down in the Surface World. During his time there, he took in Morgiana as his personal slave by using magic handcuffs on her, and took his residence within the middle east.
Hoopa remained in hiding until Heine, Aladdin, and Grell Sutcliff had found him. Not wanting to go back, he sent Morgiana to go and fight them, but during the fight he was called back into the vessel, and as such trapped. During the flight back to Japan, he just managed to trick Aladdin again into letting him out as they rested, promising to tell them some important information in regards to Amestris and King Bradley, only to get recaptured in one of his own handcuffs, keeping him stuck there. Upon their return to Japan, he and the others of Team Harmony were captured by the Slicer Brothers.
He remains as a side character for the remainder of the story.