During the two missions inside the Shining Stars base in Atlas Park, both Twinshot and Flambeaux exhibit a glitch wherein they are constantly trying to run straight at your character. This results in constant collisions, so they're constantly trying to compensate and adjust their positions, and it just doesn't stop.
As this does not happen at all with Proton and Dillo, I suspect this behavior may be related to the fact that both female characters are "introduced" by them running up to the player's location. In contrast, when the player meets Proton and Dillo, the male NPCs are standing still and the player has to approach them. So I think that, for some reason, Twinshot and Flambeaux are not getting the command to stop once they reach the player's location.