Nothing is known about Gael before the apocalypse, but it can be inferred that he was involved in gang activity.
Soon after the outbreak started, Gael and his gang started roaming the roads of Baja and killing survivors for their supplies, making them one of the most feared organizations in the area.
Gael is one of three men Nicholas Clark encounters on the road to Tijuana. He and his two companions are looting cars and killing to occasional survivor (i.e. the Older Gentleman) begging for water in his car. After Nick's radio goes off revealing his presence He and his buddies chase Nick briefly before giving up.
They encounter Nick later, walking among a herd of Infected. Gael becomes spooked by Nick's glare and becomes distracted, which allows the Infected a chance to overpower and devour him.