Date: 201809
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: Marginal
Aircraft: EMB ERJ 190/195 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Commercial; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Communication Breakdown
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Security; Deviation / Discrepancy - Procedural FAR; Flight Deck / Cabin / Aircraft Event Passenger Misconduct
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: Flight Crew Took Evasive Action; General Flight Cancelled / Delayed
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: After a 2 hour weather delay; passengers boarded for our flight from ZZZ to ZZZ1. The main door was closed and the jetway was pulled from the gate. A female passenger wanted to deplane. I called Operations and informed them we had a passenger that wanted to deplane. The jetway was pulled up and the passenger deplaned. Before the jetway pulled up; the passenger was exhibiting erratic behavior and wasn't sure if she wanted to stay on the airplane or deplane. She also switched seats on the aircraft. She told the Flight Attendant in the front of the airplane that she was homeless and had nowhere to go when she got to ZZZ1. I thought that was strange in and of itself. She (passenger) then said she needed her checked bag; but then decided that it was ok if her bag went to ZZZ1 and she didn't. Again; a very strange request from a person who just said she was homeless.The Flight Attendant didn't know her name because she had switched seats along with other passengers. The flight was half full. I was then queried by the ramp personnel if I had her name and checked bag tag ticket number; so the bag can be pulled from the cargo hold. I did not. I did not have her name and the Flight Attendant did not either. There was a [few] back and forth [between] Ops [and] the ramp personnel to go without her and keep the bag on the aircraft. [However]; the Ramp could not locate the bag because they had no ticket number or name. At first; they wanted it removed and then they didn't. At this point; I didn't have the passengers name and neither did the Ramp or Operations. I was not comfortable keeping the bag on the aircraft not knowing the passengers name and her erratic and inconsistent behavior.At one point; I was told by Operations that she was a fare jumper and it was okay if her bag went to ZZZ1. I informed Operations I was not sure what a fare jumper was and I would like the bag removed because there was just too many inconsistencies with the passenger's story and everyone's inability to produce the passenger's name. I only found out from ground personnel [her] last name. I then looked up the passenger's last name and I was able to produce the name for this report and the aforementioned.While the Company Operations Manual states that a passenger's bag can travel without the passenger domestically; there were too many unknowns with the passenger and I exercised Captain's authority and had the bag removed. I was being asked by Operations to depart and they assured me it was okay to go; but yet could not produce the passenger's name. That was not adequate for me. Captain's authority in this situation was crucial to making a last stand for a passenger exhibiting erratic behavior and a very inconsistent story for her wanting to deplane. It is paramount that Captain's authority be maintained to avoid the loopholes and the willingness of Operations to get the aircraft off the gate ASAP. I felt it was a safety issue and I was not comfortable keeping the bag on the aircraft.Any passenger who is unsure about boarding the aircraft should be met by the Ground Crew Security Coordinator.




Synopsis: Embraer ERJ Captain reported that a passenger deplaned and wanted to leave the luggage on the aircraft.