Commission for Sefirosu
Rarely, bats can deviate from the norm. Sometimes it's magical in nature; fiercer forms, breathing underwater, digging, fire resistance, etc. Othertimes they're less elegant changes; like deformities, disabilities, or conjoined twins.
If they were just sent out into the wild to find hosts on their own, they might fall prey to predators, but many hives keep them as pets, caring for them, givng them a chance to maybe even find a host.