[Fontana] says that seeing Meloni and Tergesen in a fake romance was what inspired him to make it a real one: “The Keller/Beecher thing really grew out of the dynamic between the two actors, Chris and Lee, in the sense that my original intention was simply for Keller to be a classic sexual predator, using the Beecher character. But the chemistry between the two actors onscreen was such that I went, ‘Well wait a minute, there's more here and it's much more interesting than anything that I would have conceived of.' [...] It was exciting to see the dynamic between them, so that's why I stayed with that story in terms of Beecher's development as a character.”
Part of the chemistry between the two actors came from the extent to which they invested themselves in their roles, so that even in their unscripted moments they were believable as two men in love. In fact, over the next four seasons, some of their most memorable moments would be wordless: Keller casually running his hand over Beecher's arm; the look in Beecher's eyes when he goes in to visit Keller in hospital after he has been injured; Beecher anxiously running his fingers through his hair before going in to see Keller for the first time after a long separation. The way Keller pauses for a moment before turning around when Beecher says his name.
-- from here
Ten years, guys. ♥