From LSWiki

Contents 1 Bonding Requirements 2 Known Abilities 2.1 Combat Bonuses 2.2 Attribute Modifications 2.3 Manipura Chakra 2.4 Specialty Bonuses 2.5 Charms 2.6 Additional Bonuses and Powers 2.7 Traits granted

Bonding Requirements

Looks like empathy is the main requirement, based on the failure message:

You sense that the black male panda bear feels as though you could use more affection and warmth in your life.

(One was successfully bonded with a buffed Empathy of 130 and not much else besides a couple of trains as a fresh human VV explorer)

Known Abilities

Combat Bonuses

Attribute Modifications

Manipura Chakra

Looks like Panda familiars open and charge the Manipura chakra periodically.

Specialty Bonuses

Bonus specialty degrees and access are provided as follows:

Charms

Shortly after bonding

• Standard Charms
• Tame
• Command

Somewhat frail

• Enable Darkvision

Additional Bonuses and Powers

Traits granted