From LSWiki

Bonding Requirements

"Resilient form" and "fiery spirit" - it appears that some combination of Courage, Resilience, Steadiness, and possibly Pain Tolerance meets the first requirement. Discipline and Tenacity may be other alternatives, but were not required (bonded at zero skill in one case). A large amount of Fire Affinity sufficed for the second requirement, although Twilight has stated there are other means of satisfying that.

Known Abilities

Petting the familiar

You pet Tempest with your bony right hand.
Your bony right hand is singed by contact with Tempest's orange fire, though 
you are largely unaffected by the attack.

This inflicts a small amount of fire damage on contact. Note that with enough fire affinity, this will eventually result in a very minor heal, although presumably at some cost to the familiar.

Attribute Modifications

The phoenix familiar grants its consort a large bonus to constitution and charisma.

Specialty Bonuses

Bonus specialty degrees and access are provided as follows:

• Fire Affinity
• Biofeedback
• Recuperation
• Regeneration
• Stamina
• Anatomy
• Diagnosis
• First Aid
• Pyromancy
• Empathy

Charms

• Urge

Shortly after:

• Call
• Send

Additional Bonuses and Powers

Traits granted