You do know DCA is slot-restricted, right? And that AS dropped their MIA flight for FLL, and AA picked it up? And AS flies to PHL/BOS already?

"Sure, we're your best buddies, AA, so we're going to add 4xSEA-CLT, 2xSEA-MIA, 3xSEA-PHL and 2xSEA-BOS, just like our pal DL did to us, we'll dump a bunch of capacity into your hubs and hurt your ability to get profits on those route! Because that's what partners do, right? i know we loved it when Delta did that to us, so you'll love it when we do it to you!"

You have an odd idea of "growing partnerships"... most airline executives would consider that "giving your supposed partner a middle finger when you dump extra capacity into a hub to try and chase a partner off a route". Or maybe I'm misunderstanding you-what exactly do you have in mind?

Or, to put it another way... AA has a hub in LAX. So would the AS-AA partnership grow if AA decided it was time to fly 6xLAX-SEA and 3xLAX-PDX, and maybe 1x LAX-ANC?