Board Thread:Theories/@comment-44511714-20200112082718/@comment-37493549-20200221114720

It's true that people can be influenced by their titan's previous holders, but we've only really seen this with the founding titan and the vow to renounce war. It seems like this is something only the founder can do since we haven't explicitly seen it with anyone else.

I think with Armin/Bertholdt it's more of an indirect thing due to the nature of the colossal titan. It's power is basically only good for causing huge destruction and mass murder, and both Armin and Bertholdt were pressured into using this power by their military superiors. When personality wise they both wouldn't really want to do it. Armin never even uses the colossus titan in the most recent chapters (even though it would have been very useful) presumably because of the inevitable collateral damage it would cause.

They're both basically carrying around a personal nuke every second of their lives, that's sure to change your personality somewhat.