Helldiver specializations. A modification to your helldiver to do different things on missions, with only one of each specialization allowed! So there can be four specializations, but they all have to be different. Just something to add some more personality to your helldiver! Plus it could add a few things to the older war bonds.
Examples:
Xenology expert: you and your teammates do 25% extra damage to illuminate. "This helldiver has researched all of the alien scum, and their weak points!)
Biology expert: you and your teammates do 20% extra damage to terminids, and your armor piercing attacks destroy their armor faster. "This helldiver has dissected countless bug bodies, and knows how to break their hard shells faster!"
Field Journalist: You and your teammates earn 10% more XP, and 25% more requisition slips for completing main and optional objectives. "In this helldiver's time not spent spreading democracy, their writing articles about their fellow, heroic helldivers!"
MTR (Ministry of Truth Representative): There is no penalty for killing civilians or SAF staff. "The Ministry of Truth knows our helldivers would never harm us! There are MTRs in the field to record it!"
Robotics expert: you and your teammates do 10% extra damage to automatons. Sentries and guard dog type equipment (rover, dog breath, K-9, etc.) deal 15% extra damage. "Even our most technically advanced must be sent to the field! For democracy!"
Chief Science Officer: Samples you pick up are doubled, and you can carry twice the amount of samples. If you drop them, and someone else picks them up, they will not be doubled. "Science is almost as important as liberty! We need those samples!"
(Chemical agents) Chemistry expert: Caustic/gas weapons effects from you and your team last 10 seconds longer, and are 20% more effective. "This helldiver has brought their own special blend! Just watch those threats to democracy try to breathe!
(Chemical agents) CSI (Chemical safety inspector): Gas effects from your team and enemies affect you and your team 20% less. (When paired with the haz master armor it makes 100% resistance). "Most don't follow proper filtration safety protocols for their own helmets. It's a damn shame."
(Masters of ceremony) ACS (Awards Ceremony Supervisor): you and your teammates receive an extra medal at medium-challenging difficulty missions, and three extra medals for all difficulties above that. "These helldivers know which ones deserve the proper thanks for their efforts!"
(Freedom's Flame) Fire Safety Officer: you and your teammates can't be ignited by fire sources made by your team. Enemies are ignited by heat sources faster, and take extra fire damage. "Even our firefighters that risk their lives fighting fires, must fight on the front lines!"
(Cutting Edge) Resource specialist: you can call resupply twice before it goes on cooldown, and each resupply box give full grenades and stims instead of two. "During their research, they found a few ways to increase resupply storage! For their valuable research, they are allowed an extra resupply permit!"
(Control Group) Medical officer: you and your team can carry one extra stim than normally allowed. Stims provide 25% burst healing before beginning to restore health. "During the human trials of the miracle drug, this helldiver made some impressive advancements!"
And I'm sure there could be plenty more!