Cherished by the Dragon - Dahlstrom Brothers, #1

Mustang shifter Jayden Garcia and dragon shifter Todd Dahlstrom were toddlers when they met in the same hospital room. Todd's mother couldn't soothe her frightened son and stop the boy's uncontrollable crying. Jayden crawled into his bed and wrapped his arms around him. Todd quieted as he leaned into Jayden. Too young to understand what was happening, their inner animals instinctively knew they were destined for each other, and their mothers vowed to keep them together.
When they reach puberty, they learn that Todd is unable to shift. His dragon soul has been stripped away, leaving him vulnerable to human diseases.