What Alan did was not out of character
It was exceedingly in character
Throughout this season Alan has been doing everything in his power to hold his family together.
He watched Jeff slowly decline
He watched Babe screw up and Charlie distance himself
He watched Jeff decline rapidly
He watched Charlie take Jeff’s place
He watched Babe react to Charlie decision
He watched Babe shatter when Charlie was taken
He watched Dean crash in order to help
He is still living with the guilt of everything that happened to Dean last year
He now has a little brother missing, everyone is presuming Dean’s dead.
He now has another little brother, Charlie, slowly declining in Jeff’s place - and he knows what that will do to Babe
Then Winner appears. Saying Dean is alive and Alan jumps.
He knows Charlie would willingly sacrifice himself again. He knows Babe and Jeff would disagree. He knows that Dean deserves a chance to live.
He also knows dealing with Tony is dealing with the devil.
But he’s fucking desperate
So Alan volunteered. Naïvely thinking Tony will follow through. That in doing so he’ll be saving Dean and sparring Charlie.
He was wrong. But not out of character