I'm not sure if this is the same fic or bits from two different ones. both should! be spander.
The hyena gets released and xanders personality gets pushed to the back but the hyena knows this can not last forever and so allows its 'pack' to perform a spell to unite the two. The hyena doesn't lets the scoobies out of his sight to start with and is really not lovin' Riley at all.
When xander is patrolling the hyena he sort of changes like a werewolf, he helps Oz keep control of his wolf.
Any help would be good, oh and any suggestions