Status: In game
Ed needed anger management classes. They seem to go back and forth between normal conversation and arguing all the time, especially if the adjectives short, little, or small are used. She reached him via video on the Pokegear and offered to show him the ropes in Cherrygrove. When Katara found herself traveling solo she asked to travel together with Ed and ended up with him as well as Alfons and Ieyatsu, at least for a time. They'd been travel companions ever since. They've survived soul sucking bugs, canon updates, dark type invasions, and one or two villain plots since and grown close. Katara had even started to develop feelings for him before Winry arrived. She never got around to acknowledging those feelings and instead put her focus into helping to reunite all the members of the family-- Ed, Winry, and Alphonse. It was a very big blow when he returned home.
Did I mention they argued a LOT?
He's returned to Johto without memories of his first visit. Katara hasn't had a chance to speak with him yet.