Chosen Bear by Juniper Hart

A mysterious necklace Theo found in his youth could be his only clue to defeating a faceless terrorist. It could also be the link to his destined mate.
Theo Veriday has spent his immortal life rolling with the times. He does not cling to the past, nor anticipate the future. The only bind between them is a mysterious necklace he found in his youth.
When the elusive Jackrabbit begins to taunt him in ways that only someone who knew him well would know, Theo begins to doubt himself.
But how could a faceless terrorist have any ties to him?
Simone Ruiz has always had an agenda of her own and her stealthy intelligence has managed to keep her out of trouble—until she fell onto the radar of a private military security team who would stop at nothing to see her destroyed.
When she comes head to head with the dazzling and equally dangerous Theo, she knows she’s in over her head in more ways than one, but will that be enough to stop her?