Haytham learns from Connor in the warehouse (Seq. 9) that Charles Lee murdered Ziio against his orders.

Distraught by guilt he does not fight well in battles for some time alongside his son, and Connor catches on to his change of personality and finally confronts him to revive his mentality for the sake of both their safeties during the truce, as well as a hidden wanting to become reacquainted with his father.

Hurt/comfort, possibly just a little fluff or something more, up to you.