The Gator
Footballguy
Him wanting to return and find William who ditched his(Logan's) sister? That right there explains the MiB obsession with continuing to go there for 30 years. Also explains the violence MiB shows towards Dolores.With Logan, there's no story in getting from Logan to the MiB.
We know Logan already looked down on and didn't like William, not a stretch to think William leaving Logan for 'dead' tipped Logan to the psychopath role.