Chakotay was born on a planet near the Cardassian border where his family's tribe, decendents of the aincent Rubber Tree People, had settled many years ago. He refused to accept his people's ways, and left for Starfleet Academy.
While in Starfleet, Chakotay rose to the rank of Lieutenant Commander. When his tribe's planet was turned over to the Cardassians in a peace treaty in 2370, he resigned from Starfleet and joined the Maquis.
"Cathexis" - Chakotay returns from a mission, his neural energy drained.
"Initiations" - Chakotay is targeted by a Kazon youth who must earn his warrior name.
"Tattoo" - When an away team encounters hostile natives, Chakotay has flashbacks to his childhood.
"Maneuvers" - Chakotay goes after Seska alone when the Kazon steal a transporter module.