After playing the story for a couple hours you will unlock Scout Missions. These are side missions you can do for extra cash and gear and you can invite allies to join you. Check out this guide to find out how to invite an ally to a scout mission in Attack On Titan 2.
How To Invite An Ally To A Scout Mission In Attack On Titan 2
To bring someone with you on the a Scout Mission you need to find them in the town. You can easily do this from the menu and just select the person to warp to them. When you talk to them you can invite them on a mission and change their outfits. The thing is, you can only bring one ally out to a mission with you. Doing this will increase your relationship with that character and you will have someone who can save your butt if you get caught. After they are following you, pick a Scout Mission and when you start they will join you for the mission. They will be with you until the end of the mission, no matter how many sections there are.
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