Was linked to a video of the full TIFF press conference for TKS and there was a delightful bit (@34:40) where Colin is talking about Lionel and Bertie:
Colin: [On Bertie and Lionel] I think it's slightly love at first sight quite frankly.
Geoffrey: He [Colin] actually leaned over to me last night at the climax of the film [after 'thank you my friend; thank you Your Majesty'] and said "We should have kissed".
Colin: Had Helena Bonham Carter not entered the room...
And then Seidler commented on how he didn't realize he was writing Brokeback Mountain in the Palace and Colin replies with "Well...get used to it." XD Honestly, I think a lot of the bond between the two characters comes from the relationship between these two actors.
You can watch the video here