Thanks to Lisabeth for suggesting this series:
About the series (with the help pf magic, gods bound themselves to Highlander warriors during a time of war, but the god’s lust for battle spiraled out of control)
Dangerous Highlander: A Dark Sword Novel
…inside each warrior, the gods waited. With every generation the gods moved from warrior to warrior, passed down and forever a part of the family’s bloodline. And so the Warriors were born.
Forbidden Highlander: A Dark Sword Novel