The idea behind Forked Lightning was to create a Lightning flavored but otherwise in regards to the rules identical clone of Fireball (http://www.d20pfsrd.com/magic/all-spells/f/fireball). I even copied the spell description for the most part, only adjusting where necessary. :)<br/><br/>So in case of doubt assume it works just like Fireball does. Under that premise yes, everyone in the area takes the full damage. Like with all other AoE spells in Pathfinder. Keep in mind, Aneirin is an optimized blaster at this point, so yes, that is a considerable amount of damage. Fireball itself is just as OP when it can hit many targets.