he has lore
intrigued
the one-line answer
Someone has a complex, interesting, or surprising backstory.
He has lore means there is more to this person than appears on the surface. Their history is interesting and worth discovering.
mainstream
Your coworker might use this word.
01 / in the wild
hear it move.
intrigue
he has lore. you need to hear what happened.
He has a complex interesting backstory that explains his current behavior.