Police Drone is trying to take the train.

[Wavicle]

Wife and kids waiting at home?

 

[Rudra]

The police drones and arachnos drones, the levelless always purple ones that guard places, will move to shoot mobs that enter their engagement range. And depending on how far they have to move to shoot their target, they will either return to their starting point or remain where they are. (So if they don't move very far from their assigned location, then after they despawn their target, they will often just stay where they are. At least until a reset or another mob moves them too far away.)