Pollux will use primary attack and then secondary attack. He will use secondary attack for Dutiful Retaliation.
OFFENSE & DEFENSE
Melee ◆ [Primary Attack] [dice=Fist (Fatal d10) Attack]1d20+5[/dice] | [dice=Damage]1d6+2[/dice] B damage
Melee ◆ [Secondary Attack] [dice=Swordhand (Agile, Finesse, Versatile P) Attack]1d20+7[/dice] | [dice=Damage]1d6+2[/dice] S/P damage
↺ Dutiful Retaliation - Trigger An enemy within 15 feet of you hits you with a Strike and deals damage to you. Your eidolon makes a melee unarmed Strike against the triggering enemy, even if that enemy isn't within your eidolon's reach.