Brenin. Savage Dragons, #4

Brenin Savage is a blue dragon shifter who has lived for thousands of years-but nothing in all that time prepares him for the moment he finds his mate waiting tables in a small-town diner. Lisa Manchester is a widowed mother barely keeping her head above water. Between raising her tender-hearted seven-year-old son, working two jobs, and dealing with a manipulative mother-in-law, she doesn't have room in her life for a powerful immortal claiming she belongs to him-heart and soul.
When a brutal playground attack leaves her son shaken and the school turning a blind eye, Lisa's world begins to unravel. Then she narrowly avoids a deadly accident-saved by a magic she doesn't believe in and a dragon she doesn't yet trust. Brenin vows to protect Lisa and her son with his life-and his fire. But convincing a fiercely independent woman that he wants a partner, not a possession, may be his greatest challenge yet.
Because loving a dragon means stepping into a world of immortality, ancient magic, and enemies hiding in plain sight. And Brenin will burn down the world before he lets anything harm what is his.