short version only your brother and his alters can explain to you what is going on with him and his alters, and what he and his alters are capable of doing.

in general dissociative type alternate personalities have their own jobs, purpose, reasons for being..they have their own thoughts, behaviors, how they perceive their self and others.

how does that fit in with what you posted....one alter can think the host is a royal pain in the behind while another alter may think the host is cool, another may believe the host has disappeared, left, or even died, or they may believe there is no host or they killed the host..

line in the sand if this alter believes they killed the host and left him in a dumpster then thats what it means...they think the host is dead in a dumpster.

that said I did have an alter who's job,purpose, reason for being was to be extremely sarcastic and prevent me from being hassled, bullied, ...by family and friends. if one of my friends called me more than once a day that alter would answer the phone with...Amandalouise has died, at her request there was no funeral any donations can be given to the charity of your choice. another alter if they felt I needed a break from family and friends would get quite graphic in how I killed myself. I cant count how many times I would pass someone on the street and they would look like they had seen my ghost lol

again only your brother and his alters can tell you what is going on, why and what it means.